[PATCH] mmc: bcm2835_sdhci: Parse generic MMC device tree properties

[Peter Robinson]

On Sat, 9 May 2026 at 22:06, Liel Harel <liel.harel at gmail.com> wrote:
>
> From: Liel Harel <liel.harel at gmail.com>
>
> The bcm2835 SDHCI driver sets up the MMC host configuration via
> sdhci_setup_cfg(), but does not parse generic MMC device tree
> properties.
>
> As a result, properties such as bus-width are ignored. On Raspberry Pi
> Compute Module 4, the eMMC node describes an 8-bit bus, but U-Boot
> initialized the device as 4-bit.
>
> Call mmc_of_parse() before sdhci_setup_cfg() so that generic MMC
> properties are folded into the host configuration before the MMC core
> selects the bus width.
>
> Before this change, mmc info reported:
>
>     Bus Speed: 52000000
>     Bus Width: 4-bit
>
> After this change, mmc info reports:
>
>     Bus Speed: 52000000
>     Bus Width: 8-bit
>
> Tested on Raspberry Pi Compute Module 4 with onboard eMMC.
>
> Signed-off-by: Liel Harel <liel.harel at gmail.com>
Reviewed-by: Peter Robinson <pbrobinson at gmail.com>
Tested-by: Peter Robinson <pbrobinson at gmail.com> # on the CM4 as well

Thanks

> ---
>  drivers/mmc/bcm2835_sdhci.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/mmc/bcm2835_sdhci.c b/drivers/mmc/bcm2835_sdhci.c
> index 655d9902dfa..efa4d14f5da 100644
> --- a/drivers/mmc/bcm2835_sdhci.c
> +++ b/drivers/mmc/bcm2835_sdhci.c
> @@ -219,6 +219,10 @@ static int bcm2835_sdhci_probe(struct udevice *dev)
>         host->mmc = &plat->mmc;
>         host->mmc->dev = dev;
>
> +       ret = mmc_of_parse(dev, &plat->cfg);
> +       if (ret)
> +               return ret;
> +
>         ret = sdhci_setup_cfg(&plat->cfg, host, emmc_freq, MIN_FREQ);
>         if (ret) {
>                 debug("%s: Failed to setup SDHCI (err=%d)\n", __func__, ret);
> --
> 2.43.0
>