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openmptcprouter/6.12/target/linux/bcm27xx/patches-6.12/950-0501-spi-dw-Clamp-the-minimum-clock-speed.patch
Ycarus (Yannick Chabanois) bdb9b0046f Add bcm27xx 6.12 test support
2024-12-20 14:17:26 +01:00

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1.1 KiB
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From 442d4c5a1042ee1cd74f46877607e5ab22a3a562 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Wed, 31 Jul 2024 10:55:19 +0100
Subject: [PATCH 501/697] spi: dw: Clamp the minimum clock speed
The DW SPI interface has a 16-bit clock divider, where the bottom bit
of the divisor must be 0. Limit how low the clock speed can go to
prevent the clock divider from being truncated, as that could lead to
a much higher clock rate than requested.
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
drivers/spi/spi-dw-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -399,7 +399,7 @@ void dw_spi_update_config(struct dw_spi
dw_writel(dws, DW_SPI_CTRLR1, cfg->ndf ? cfg->ndf - 1 : 0);
/* Note DW APB SSI clock divider doesn't support odd numbers */
- clk_div = (DIV_ROUND_UP(dws->max_freq, cfg->freq) + 1) & 0xfffe;
+ clk_div = min(DIV_ROUND_UP(dws->max_freq, cfg->freq) + 1, 0xfffe) & 0xfffe;
speed_hz = dws->max_freq / clk_div;
if (dws->current_freq != speed_hz) {