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mmc: sdhci-esdhc-imx: widen auto-tuning window for standard tuning

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Expand the auto-tuning window width from 2 to 3 for standard tuning to
account for sampling point shifts caused by temperature change. This change
is based on hardware recommendation, providing 50% more margin for the
auto-tuning logic to locate valid sampling points.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Signed-off-by: Luke Wang <ziniu.wang_1@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20250409075550.3413032-4-ziniu.wang_1@nxp.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Haibo Chen 2025-04-09 15:55:47 +08:00 • committed by Ulf Hansson
parent d0aac7d811
commit be953af79c
1 changed files with 13 additions and 0 deletions
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13
drivers/mmc/host/sdhci-esdhc-imx.c
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@ -108,6 +108,7 @@
#define ESDHC_TUNING_CTRL 0xcc
#define ESDHC_STD_TUNING_EN (1 << 24)
#define ESDHC_TUNING_WINDOW_MASK GENMASK(22, 20)
/* NOTE: the minimum valid tuning start tap for mx6sl is 1 */
#define ESDHC_TUNING_START_TAP_DEFAULT 0x1
#define ESDHC_TUNING_START_TAP_MASK 0x7f
@ -209,6 +210,8 @@
/* The IP does not have GPIO CD wake capabilities */
#define ESDHC_FLAG_SKIP_CD_WAKE BIT(18)
#define ESDHC_AUTO_TUNING_WINDOW 3
enum wp_types {
ESDHC_WP_NONE, /* no WP, neither controller nor gpio */
ESDHC_WP_CONTROLLER, /* mmc controller internal WP */
@ -1553,6 +1556,16 @@ static void sdhci_esdhc_imx_hwinit(struct sdhci_host *host)
<< ESDHC_TUNING_STEP_SHIFT;
}
/*
* Config the tuning window to the hardware suggested value 3.
* This tuning window is used for auto tuning logic. The default
* tuning window is 2, here change to 3 make the window a bit
* wider, give auto tuning enough space to handle the sample
* point shift cause by temperature change.
*/
tmp &= ~ESDHC_TUNING_WINDOW_MASK;
tmp |= FIELD_PREP(ESDHC_TUNING_WINDOW_MASK, ESDHC_AUTO_TUNING_WINDOW);
/* Disable the CMD CRC check for tuning, if not, need to
* add some delay after every tuning command, because
* hardware standard tuning logic will directly go to next