It seems that there are maximum timings for mdio accesses that can be hit when the system is under load and the thread is scheduled during a read or write access. Since there is no way of knowing if this happens as there is not even a parity bit, try to work around it by disabling interrupts during any gpio-mdio accesses. Performance impact seems to be neglectable, as mdio accesses are not that often. Hopefully fixes #19500. Signed-off-by: Jonas Gorski <jogo@openwrt.org> SVN-Revision: 46012master
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From 66e584435ac0de6e0abeb6d7166fe4fe25d6bb73 Mon Sep 17 00:00:00 2001
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From: Jonas Gorski <jogo@openwrt.org>
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Date: Tue, 16 Jun 2015 13:15:08 +0200
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Subject: [PATCH] phy/mdio-bitbang: prevent rescheduling during command
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It seems some phys have some maximum timings for accessing the MDIO line,
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resulting in bit errors under cpu stress. Prevent this from happening by
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disabling interrupts when sending commands.
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Signed-off-by: Jonas Gorski <jogo@openwrt.org>
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---
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drivers/net/phy/mdio-bitbang.c | 9 +++++++++
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1 file changed, 9 insertions(+)
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--- a/drivers/net/phy/mdio-bitbang.c
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+++ b/drivers/net/phy/mdio-bitbang.c
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@@ -17,6 +17,7 @@
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* kind, whether express or implied.
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*/
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+#include <linux/irqflags.h>
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#include <linux/module.h>
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#include <linux/mdio-bitbang.h>
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#include <linux/types.h>
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@@ -156,7 +157,9 @@ static int mdiobb_read(struct mii_bus *b
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{
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struct mdiobb_ctrl *ctrl = bus->priv;
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int ret, i;
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+ long flags;
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+ local_irq_save(flags);
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if (reg & MII_ADDR_C45) {
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reg = mdiobb_cmd_addr(ctrl, phy, reg);
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mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg);
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@@ -169,13 +172,17 @@ static int mdiobb_read(struct mii_bus *b
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ret = mdiobb_get_num(ctrl, 16);
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mdiobb_get_bit(ctrl);
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+ local_irq_restore(flags);
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+
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return ret;
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}
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static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val)
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{
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struct mdiobb_ctrl *ctrl = bus->priv;
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+ long flags;
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+ local_irq_save(flags);
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if (reg & MII_ADDR_C45) {
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reg = mdiobb_cmd_addr(ctrl, phy, reg);
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mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg);
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@@ -190,6 +197,8 @@ static int mdiobb_write(struct mii_bus *
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ctrl->ops->set_mdio_dir(ctrl, 0);
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mdiobb_get_bit(ctrl);
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+ local_irq_restore(flags);
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+
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return 0;
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}
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