From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory CLEMENT Subject: [PATCH v2 1/2] i2c-mv64xxx: Fix timing issue on Armada XP (errata FE-8471889) Date: Tue, 18 Jun 2013 17:40:23 +0200 Message-ID: <1371570024-11613-2-git-send-email-gregory.clement@free-electrons.com> References: <1371570024-11613-1-git-send-email-gregory.clement@free-electrons.com> Return-path: In-Reply-To: <1371570024-11613-1-git-send-email-gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Jason Cooper , Andrew Lunn , Gregory CLEMENT , Thomas Petazzoni , Ezequiel Garcia , Sebastian Hesselbarth , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Zbigniew Bodek List-Id: linux-i2c@vger.kernel.org From: Zbigniew Bodek All the Armada XP (mv78230, mv78260 and mv78460) have a silicon issue in the I2C controller which violate the i2c repeated start timing. The I2C standard requires a minimum of 4.7us for the repeated start condition whereas the I2C controller of the Armada XP this time is 2.9us. So this patch adds a 5us delay for the start case only if the mv64xxx_i2c_errata_delay flag is set. [gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org: Use the delay flasg as per-I2C controller variable] [gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org: Merge the incoming commits into this single one] [gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org: Reword the commit log] Signed-off-by: Gregory CLEMENT Signed-off-by: Zbigniew Bodek --- drivers/i2c/busses/i2c-mv64xxx.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c index 1a3abd6..74f8fcb 100644 --- a/drivers/i2c/busses/i2c-mv64xxx.c +++ b/drivers/i2c/busses/i2c-mv64xxx.c @@ -23,6 +23,7 @@ #include #include #include +#include /* Register defines */ #define MV64XXX_I2C_REG_SLAVE_ADDR 0x00 @@ -103,6 +104,10 @@ struct mv64xxx_i2c_data { int rc; u32 freq_m; u32 freq_n; + +/* 5us delay in order to avoid repeated start timing violation */ + bool mv64xxx_i2c_errata_delay; + #if defined(CONFIG_HAVE_CLK) struct clk *clk; #endif @@ -252,6 +257,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data) writel(drv_data->cntl_bits, drv_data->reg_base + MV64XXX_I2C_REG_CONTROL); drv_data->block = 0; + if (drv_data->mv64xxx_i2c_errata_delay) + udelay(5); + wake_up(&drv_data->waitq); break; @@ -300,6 +308,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data) writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_STOP, drv_data->reg_base + MV64XXX_I2C_REG_CONTROL); drv_data->block = 0; + if (drv_data->mv64xxx_i2c_errata_delay) + udelay(5); + wake_up(&drv_data->waitq); break; @@ -592,6 +603,9 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data, * So hard code the value to 1 second. */ drv_data->adapter.timeout = HZ; + + if (of_machine_is_compatible("marvell,armadaxp")) + drv_data->mv64xxx_i2c_errata_delay = 1; out: return rc; #endif -- 1.8.1.2