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mmc: core: Parse and use the new max-sd-hs-hz DT property

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Introduce a new device tree flag to cap the maximum High-Speed (HS)
mode frequency for SD cards, accommodating board-specific
electrical limitations which cannot support the default 50Mhz HS
frequency and others.

Signed-off-by: Sarthak Garg <quic_sartgarg@quicinc.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Sarthak Garg 2025-09-08 16:11:21 +05:30 committed by Ulf Hansson
parent 98682689a1
commit f338529ca9
3 changed files with 4 additions and 1 deletions
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2
drivers/mmc/core/host.c
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@ -302,6 +302,8 @@ int mmc_of_parse(struct mmc_host *host)
/* f_max is obtained from the optional "max-frequency" property */
device_property_read_u32(dev, "max-frequency", &host->f_max);
device_property_read_u32(dev, "max-sd-hs-hz", &host->max_sd_hs_hz);
/*
* Configure CD and WP pins. They are both by default active low to
* match the SDHCI spec. If GPIOs are provided for CD and / or WP, the

2
drivers/mmc/core/sd.c
View File

@ -359,7 +359,7 @@ static int mmc_read_switch(struct mmc_card *card)
}
if (status[13] & SD_MODE_HIGH_SPEED)
card->sw_caps.hs_max_dtr = HIGH_SPEED_MAX_DTR;
card->sw_caps.hs_max_dtr = card->host->max_sd_hs_hz ?: HIGH_SPEED_MAX_DTR;
if (card->scr.sda_spec3) {
card->sw_caps.sd3_bus_mode = status[13];

1
include/linux/mmc/host.h
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@ -576,6 +576,7 @@ struct mmc_host {
int hsq_depth;
u32 err_stats[MMC_ERR_MAX];
u32 max_sd_hs_hz;
unsigned long private[] ____cacheline_aligned;
};