From: Inochi Amaoto <inochiama@gmail.com>
Date: Thu, 21 May 2026 07:21:20 +0000 (+0800)
Subject: mmc: litex_mmc: Use DIV_ROUND_UP for more accurate clock calculation
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=b837e38c255dd9f8b53511d52e87f1fda32b3dfe;p=thirdparty%2Fkernel%2Flinux.git

mmc: litex_mmc: Use DIV_ROUND_UP for more accurate clock calculation

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: 92e099104729 ("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>
---

diff --git a/drivers/mmc/host/litex_mmc.c b/drivers/mmc/host/litex_mmc.c
index d2f19c2dc673..52571bb17c61 100644
--- a/drivers/mmc/host/litex_mmc.c
+++ b/drivers/mmc/host/litex_mmc.c
@@ -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;
 }