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

[Philipp Zabel]

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