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270 lines
8.3 KiB
270 lines
8.3 KiB
From 446e5857ddeac1cae84ec54d64b748820b5b455a Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Thu, 31 Mar 2016 15:44:53 +0100
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Subject: [PATCH] bcm2835-sdhost: Precalc divisors and overclocks
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Recalculating the clock divisors when the core clock changes is wasteful
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and makes it harder to manage the overclock settings. Instead,
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precalculate them and only report significant changes.
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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drivers/mmc/host/bcm2835-sdhost.c | 152 ++++++++++++++++++++++----------------
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1 file changed, 88 insertions(+), 64 deletions(-)
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--- a/drivers/mmc/host/bcm2835-sdhost.c
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+++ b/drivers/mmc/host/bcm2835-sdhost.c
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@@ -154,12 +154,15 @@ struct bcm2835_host {
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u32 pio_timeout; /* In jiffies */
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int clock; /* Current clock speed */
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+ int clocks[2];
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bool slow_card; /* Force 11-bit divisor */
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unsigned int max_clk; /* Max src clock freq */
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- unsigned int min_clk; /* Min src clock freq */
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- unsigned int cur_clk; /* Current src clock freq */
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+ unsigned int src_clks[2]; /* Min/max src clock freqs */
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+ unsigned int cur_clk_idx; /* Index of current clock */
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+ unsigned int next_clk_idx; /* Next clock index */
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+ unsigned int cdivs[2];
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struct tasklet_struct finish_tasklet; /* Tasklet structures */
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@@ -213,7 +216,7 @@ struct bcm2835_host {
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u32 delay_after_stop; /* minimum time between stop and subsequent data transfer */
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u32 delay_after_this_stop; /* minimum time between this stop and subsequent data transfer */
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u32 overclock_50; /* frequency to use when 50MHz is requested (in MHz) */
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- u32 overclock; /* Current frequency if overclocked, else zero */
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+ u32 prev_overclock_50;
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u32 pio_limit; /* Maximum block count for PIO (0 = always DMA) */
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u32 sectors; /* Cached card size in sectors */
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@@ -1509,10 +1512,35 @@ static irqreturn_t bcm2835_sdhost_irq(in
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return result;
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}
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+static void bcm2835_sdhost_select_clock(struct bcm2835_host *host, int idx)
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+{
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+ unsigned int clock = host->clocks[idx];
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+ unsigned int cdiv = host->cdivs[idx];
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+
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+ host->mmc->actual_clock = clock;
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+ host->ns_per_fifo_word = (1000000000/clock) *
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+ ((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
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+
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+ host->cdiv = cdiv;
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+ bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
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+
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+ /* Set the timeout to 500ms */
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+ bcm2835_sdhost_write(host, clock/2, SDTOUT);
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+
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+ host->cur_clk_idx = host->next_clk_idx = idx;
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+
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+ if (host->debug)
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+ pr_info("%s: clock=%d -> src_clk=%d, cdiv=%x (actual %d)\n",
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+ mmc_hostname(host->mmc), host->clock,
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+ host->src_clks[idx], host->cdiv,
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+ host->mmc->actual_clock);
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+}
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+
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void bcm2835_sdhost_set_clock(struct bcm2835_host *host)
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{
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int div = 0; /* Initialized for compiler warning */
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unsigned int clock = host->clock;
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+ int clk_idx;
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if (host->debug)
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pr_info("%s: set_clock(%d)\n", mmc_hostname(host->mmc), clock);
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@@ -1553,53 +1581,45 @@ void bcm2835_sdhost_set_clock(struct bcm
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return;
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}
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- div = host->cur_clk / clock;
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- if (div < 2)
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- div = 2;
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- if ((host->cur_clk / div) > clock)
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- div++;
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- div -= 2;
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-
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- if (div > SDCDIV_MAX_CDIV)
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- div = SDCDIV_MAX_CDIV;
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-
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- clock = host->cur_clk / (div + 2);
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- host->mmc->actual_clock = clock;
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-
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- /* Calibrate some delays */
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-
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- host->ns_per_fifo_word = (1000000000/clock) *
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- ((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
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+ /* Calculate the clock divisors */
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+ for (clk_idx = 0; clk_idx <= host->variable_clock; clk_idx++)
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+ {
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+ unsigned int cur_clk = host->src_clks[clk_idx];
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+ unsigned int actual_clock;
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- if (clock > host->clock) {
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- /* Save the closest value, to make it easier
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- to reduce in the event of error */
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- host->overclock_50 = (clock/MHZ);
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-
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- if (clock != host->overclock) {
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- pr_warn("%s: overclocking to %dHz\n",
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- mmc_hostname(host->mmc), clock);
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- host->overclock = clock;
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+ div = cur_clk / clock;
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+ if (div < 2)
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+ div = 2;
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+ if ((cur_clk / div) > clock)
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+ div++;
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+ div -= 2;
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+
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+ if (div > SDCDIV_MAX_CDIV)
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+ div = SDCDIV_MAX_CDIV;
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+ actual_clock = cur_clk / (div + 2);
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+
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+ host->cdivs[clk_idx] = div;
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+ host->clocks[clk_idx] = actual_clock;
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+
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+ if (host->overclock_50 != host->prev_overclock_50) {
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+ const char *clk_name = "";
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+ if (host->variable_clock)
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+ clk_name = clk_idx ? " (turbo)" : " (normal)";
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+ if (actual_clock > host->clock)
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+ pr_info("%s: overclocking to %dHz%s\n",
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+ mmc_hostname(host->mmc),
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+ actual_clock, clk_name);
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+ else if ((host->overclock_50 < 50) && (clk_idx == 0))
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+ pr_info("%s: cancelling overclock%s\n",
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+ mmc_hostname(host->mmc),
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+ host->variable_clock ? "s" : "");
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}
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}
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- else if (host->overclock)
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- {
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- host->overclock = 0;
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- if (clock == 50 * MHZ)
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- pr_warn("%s: cancelling overclock\n",
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- mmc_hostname(host->mmc));
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- }
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- host->cdiv = div;
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- bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
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+ if (host->clock == 50*MHZ)
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+ host->prev_overclock_50 = host->overclock_50;
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- /* Set the timeout to 500ms */
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- bcm2835_sdhost_write(host, host->mmc->actual_clock/2, SDTOUT);
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-
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- if (host->debug)
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- pr_info("%s: clock=%d -> cur_clk=%d, cdiv=%x (actual clock %d)\n",
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- mmc_hostname(host->mmc), host->clock,
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- host->cur_clk, host->cdiv, host->mmc->actual_clock);
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+ bcm2835_sdhost_select_clock(host, host->cur_clk_idx);
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}
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static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
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@@ -1657,6 +1677,9 @@ static void bcm2835_sdhost_request(struc
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spin_lock_irqsave(&host->lock, flags);
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+ if (host->next_clk_idx != host->cur_clk_idx)
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+ bcm2835_sdhost_select_clock(host, host->next_clk_idx);
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+
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WARN_ON(host->mrq != NULL);
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host->mrq = mrq;
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@@ -1719,11 +1742,7 @@ static int bcm2835_sdhost_cpufreq_callba
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return NOTIFY_BAD;
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break;
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case CPUFREQ_POSTCHANGE:
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- if (freq->new > freq->old)
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- host->cur_clk = host->max_clk;
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- else
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- host->cur_clk = host->min_clk;
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- bcm2835_sdhost_set_clock(host);
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+ host->next_clk_idx = (freq->new > freq->old);
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up(&host->cpufreq_semaphore);
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break;
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default:
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@@ -1763,8 +1782,11 @@ static void bcm2835_sdhost_set_ios(struc
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ios->clock, ios->power_mode, ios->bus_width,
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ios->timing, ios->signal_voltage, ios->drv_type);
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- if (ios->clock && !host->cur_clk)
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- host->cur_clk = get_core_clock(RPI_FIRMWARE_GET_CLOCK_RATE);
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+ if (ios->clock && (host->cur_clk_idx == -1)) {
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+ unsigned int cur_clk =
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+ get_core_clock(RPI_FIRMWARE_GET_CLOCK_RATE);
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+ host->cur_clk_idx = (cur_clk == host->src_clks[0]) ? 0 : 1;
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+ }
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spin_lock_irqsave(&host->lock, flags);
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@@ -1854,11 +1876,12 @@ static void bcm2835_sdhost_tasklet_finis
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/* Drop the overclock after any data corruption, or after any
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error overclocked */
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- if (host->overclock) {
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+ if (host->clock > 50*MHZ) {
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if ((mrq->cmd && mrq->cmd->error) ||
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(mrq->data && mrq->data->error) ||
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(mrq->stop && mrq->stop->error)) {
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- host->overclock_50--;
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+ host->overclock_50 = (host->clock/MHZ) - 1;
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+
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pr_warn("%s: reducing overclock due to errors\n",
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mmc_hostname(host->mmc));
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bcm2835_sdhost_set_clock(host);
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@@ -2022,7 +2045,7 @@ static int bcm2835_sdhost_probe(struct p
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struct bcm2835_host *host;
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struct mmc_host *mmc;
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const __be32 *addr;
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- unsigned int max_clk;
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+ unsigned int max_clk, min_clk;
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int ret;
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pr_debug("bcm2835_sdhost_probe\n");
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@@ -2128,12 +2151,8 @@ static int bcm2835_sdhost_probe(struct p
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else
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mmc->caps |= MMC_CAP_4_BIT_DATA;
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- ret = bcm2835_sdhost_add_host(host);
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- if (ret)
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- goto err;
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-
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/* Query the core clock frequencies */
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- host->min_clk = get_core_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE);
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+ min_clk = get_core_clock(RPI_FIRMWARE_GET_MIN_CLOCK_RATE);
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max_clk = get_core_clock(RPI_FIRMWARE_GET_MAX_CLOCK_RATE);
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if (max_clk != host->max_clk) {
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pr_warn("%s: Expected max clock %d, found %d\n",
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@@ -2141,19 +2160,24 @@ static int bcm2835_sdhost_probe(struct p
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host->max_clk = max_clk;
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}
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- if (host->min_clk != host->max_clk) {
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+ host->src_clks[0] = min_clk;
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+ host->cur_clk_idx = -1;
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+ if (max_clk != min_clk) {
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+ host->src_clks[1] = max_clk;
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host->cpufreq_nb.notifier_call =
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bcm2835_sdhost_cpufreq_callback;
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sema_init(&host->cpufreq_semaphore, 1);
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cpufreq_register_notifier(&host->cpufreq_nb,
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CPUFREQ_TRANSITION_NOTIFIER);
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host->variable_clock = 1;
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- host->cur_clk = 0; /* Get this later */
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} else {
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host->variable_clock = 0;
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- host->cur_clk = host->max_clk;
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}
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+ ret = bcm2835_sdhost_add_host(host);
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+ if (ret)
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+ goto err;
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+
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platform_set_drvdata(pdev, host);
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pr_debug("bcm2835_sdhost_probe -> OK\n");
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