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45 lines
1.5 KiB
Diff
45 lines
1.5 KiB
Diff
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From 622a9f1ce0c53f661bd323fa3e3b071f5a3733b5 Mon Sep 17 00:00:00 2001
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From: Alex Crawford <raspberrypi/linux@code.acrawford.com>
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Date: Fri, 28 Jan 2022 13:36:51 -0800
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Subject: [PATCH] i2c: bcm2835: Make clock-stretch timeout configurable
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The default clock-stretch timeout is 35 mS, which works well for
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SMBus, but there are some I2C devices which can stretch the clock even
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longer. Rather than trying to prescribe a safe default for everyone,
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allow the timeout to be configured.
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Signed-off-by: Alex Crawford <raspberrypi/linux@code.acrawford.com>
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---
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drivers/i2c/busses/i2c-bcm2835.c | 10 +++++++---
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1 file changed, 7 insertions(+), 3 deletions(-)
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--- a/drivers/i2c/busses/i2c-bcm2835.c
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+++ b/drivers/i2c/busses/i2c-bcm2835.c
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@@ -60,6 +60,10 @@ static unsigned int debug;
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module_param(debug, uint, 0644);
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MODULE_PARM_DESC(debug, "1=err, 2=isr, 3=xfer");
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+static unsigned int clk_tout_ms = 35; /* SMBUs-recommended 35ms */
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+module_param(clk_tout_ms, uint, 0644);
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+MODULE_PARM_DESC(clk_tout_ms, "clock-stretch timeout (mS)");
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+
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#define BCM2835_DEBUG_MAX 512
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struct bcm2835_debug {
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struct i2c_msg *msg;
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@@ -219,12 +223,12 @@ static int clk_bcm2835_i2c_set_rate(stru
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(redl << BCM2835_I2C_REDL_SHIFT));
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/*
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- * Set the clock stretch timeout to the SMBUs-recommended 35ms.
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+ * Set the clock stretch timeout.
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*/
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- if (rate > 0xffff*1000/35)
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+ if (rate > 0xffff*1000/clk_tout_ms)
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clk_tout = 0xffff;
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else
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- clk_tout = 35*rate/1000;
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+ clk_tout = clk_tout_ms*rate/1000;
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bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_CLKT, clk_tout);
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