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mmc: litex_mmc: Use DIV_ROUND_UP for more accurate clock calculation

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commit b837e38c25 upstream.

The previous clock uses roundup_pow_of_two() to calculate the core
clock frequency. It does not meet the actual hardware meaning.
The actual frequency is calculated by "ref_clk / ((div >> 1) << 1)".

Fix the clock divider calculation.

Fixes: 92e0991047 ("mmc: Add driver for LiteX's LiteSDCard interface")
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Reviewed-by: Gabriel Somlo <gsomlo@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulfh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Inochi Amaoto
2026-06-19 13:44:03 +02:00
committed by Greg Kroah-Hartman
parent a0a4600b39
commit 8bcbedce9b
1 changed files with 3 additions and 3 deletions
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drivers/mmc/host/litex_mmc.c
+3 -3
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@@ -16,6 +16,7 @@
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/litex.h>
#include <linux/math.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
@@ -436,11 +437,10 @@ static void litex_mmc_setclk(struct litex_mmc_host *host, unsigned int freq)
struct device *dev = mmc_dev(host->mmc);
u32 div;
div = freq ? host->ref_clk / freq : 256U;
div = roundup_pow_of_two(div);
div = freq ? DIV_ROUND_UP(host->ref_clk, freq) : 256U;
div = clamp(div, 2U, 256U);
dev_dbg(dev, "sd_clk_freq=%d: set to %d via div=%d\n",
freq, host->ref_clk / div, div);
freq, host->ref_clk / ((div + 1) & ~1U), div);
litex_write16(host->sdphy + LITEX_PHY_CLOCKERDIV, div);
host->sd_clk = freq;
}