linux-kernel - Re: [PATCHv1 08/19] mmc: sdhci-of-dwcmshc: add reset call back for rockchip Socs

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Message-ID: <0ac35b47-720e-ae99-45d2-3f8d63868a1e@gmail.com>
Date:   Sat, 23 Apr 2022 13:32:35 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sebastian Reichel <sebastian.reichel@...labora.com>,
        Heiko Stuebner <heiko@...ech.de>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        linux-mmc@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel@...ts.collabora.co.uk,
        Yifeng Zhao <yifeng.zhao@...k-chips.com>, kernel@...labora.com
Subject: Re: [PATCHv1 08/19] mmc: sdhci-of-dwcmshc: add reset call back for
 rockchip Socs

22.04.2022 20:09, Sebastian Reichel пишет:
> From: Yifeng Zhao <yifeng.zhao@...k-chips.com>
> 
> The reset function build in the SDHCI will not reset the logic
> circuit related to the tuning function, which may cause data
> reading errors. Resetting the complete SDHCI controller through
> the reset controller fixes the issue.
> 
> Signed-off-by: Yifeng Zhao <yifeng.zhao@...k-chips.com>
> [rebase]
> Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
> ---
>  drivers/mmc/host/sdhci-of-dwcmshc.c | 28 +++++++++++++++++++++++++++-
>  1 file changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index bac874ab0b33..d95ae6ca1256 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -15,6 +15,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/reset.h>
>  #include <linux/sizes.h>
>  
>  #include "sdhci-pltfm.h"
> @@ -63,6 +64,7 @@
>  struct rk3568_priv {
>  	/* Rockchip specified optional clocks */
>  	struct clk_bulk_data rockchip_clks[RK3568_MAX_CLKS];
> +	struct reset_control *reset;
>  	u8 txclk_tapnum;
>  };
>  
> @@ -255,6 +257,23 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
>  	sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_STRBIN);
>  }
>  
> +static void rk35xx_sdhci_reset(struct sdhci_host *host, u8 mask)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct dwcmshc_priv *dwc_priv = sdhci_pltfm_priv(pltfm_host);
> +	struct rk35xx_priv *priv = dwc_priv->priv;
> +
> +	if (mask & SDHCI_RESET_ALL) {
> +		if (!IS_ERR_OR_NULL(priv->reset)) {

priv->reset can't be a error ptr since probe fails on error.

> +			reset_control_assert(priv->reset);
> +			udelay(1);
> +			reset_control_deassert(priv->reset);
> +		}
> +	}
> +
> +	sdhci_reset(host, mask);
> +}
> +
>  static const struct sdhci_ops sdhci_dwcmshc_ops = {
>  	.set_clock		= sdhci_set_clock,
>  	.set_bus_width		= sdhci_set_bus_width,
> @@ -269,7 +288,7 @@ static const struct sdhci_ops sdhci_dwcmshc_rk3568_ops = {
>  	.set_bus_width		= sdhci_set_bus_width,
>  	.set_uhs_signaling	= dwcmshc_set_uhs_signaling,
>  	.get_max_clock		= sdhci_pltfm_clk_get_max_clock,
> -	.reset			= sdhci_reset,
> +	.reset			= rk35xx_sdhci_reset,
>  	.adma_write_desc	= dwcmshc_adma_write_desc,
>  };
>  
> @@ -292,6 +311,13 @@ static int dwcmshc_rk3568_init(struct sdhci_host *host, struct dwcmshc_priv *dwc
>  	int err;
>  	struct rk3568_priv *priv = dwc_priv->priv;
>  
> +	priv->reset = devm_reset_control_array_get_exclusive(mmc_dev(host->mmc));

The devm_reset_control_array_get_exclusive() never returns NULL.

The devm_reset_control_array_get_optional_exclusive(() may return NULL
if reset is missing in DT, perhaps that's what you actually want?

> +	if (IS_ERR_OR_NULL(priv->reset)) {
> +		err = PTR_ERR(priv->reset);

NULL isn't a error

> +		dev_err(mmc_dev(host->mmc), "failed to get reset control %d\n", err);

dev_err_probe()?