Re: [PATCH v6 17/17] mmc: sdhci-cadence: Support mmc hardware reset

Philipp Zabel
2022-08-22T07:04:39Z

Hi Brad,

On Sa, 2022-08-20 at 12:57 -0700, Brad Larson wrote:
[...]
> +static void sdhci_mmc_hw_reset(struct mmc_host *mmc)
> +{
> + struct sdhci_host *host = mmc_priv(mmc);
> + struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
> +
> + dev_info(mmc_dev(host->mmc), "emmc hardware reset\n");
> +
> + reset_control_assert(priv->rst_hw);
> + /* For eMMC, minimum is 1us but give it 9us for good measure */
> + udelay(9);

At a glance, this seems excessive. Is there a reason 9 us is better
than, say, 2 or 3?

[...]
> @@ -520,6 +538,17 @@ static int sdhci_cdns_probe(struct platform_device *pdev)
>   if (ret)
>   goto free;
>
>
>
>
> + if (host->mmc->caps & MMC_CAP_HW_RESET) {
> + priv->rst_hw = devm_reset_control_get_optional_exclusive(dev, "hw");

This should be described in cdns,sdhci.yaml first.

regards
Philipp