Introduce a new device tree flag to cap the maximum High-Speed (HS)
mode frequency for SD cards, accommodating board-specific
constraints such as the inclusion of a level shifter which cannot
support the default 50Mhz HS frequency and others.
Signed-off-by: Sarthak Garg <quic_sartgarg@xxxxxxxxxxx>
---
drivers/mmc/core/host.c | 2 ++
drivers/mmc/core/sd.c | 2 +-
include/linux/mmc/host.h | 1 +
3 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index dacb5bd9bb71..3fe6ae56a6ae 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -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
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index ec02067f03c5..67cd63004829 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -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];
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 68f09a955a90..a698b4b02d95 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -565,6 +565,7 @@ struct mmc_host {
int hsq_depth;
u32 err_stats[MMC_ERR_MAX];
+ unsigned int max_sd_hs_hz;
unsigned long private[] ____cacheline_aligned;
};
--
2.34.1
