linux-kernel - Re: [PATCH 3/3] mmc: mediatek: add optional module reset property

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Message-ID: <f65aeebb6c372a7138e496a30ce39f879d4e24ed.camel@pengutronix.de>
Date:   Wed, 12 Aug 2020 14:08:19 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Wenbin Mei <wenbin.mei@...iatek.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     Chaotian Jing <chaotian.jing@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        srv_heupstream@...iatek.com
Subject: Re: [PATCH 3/3] mmc: mediatek: add optional module reset property

On Wed, 2020-08-12 at 17:37 +0800, Wenbin Mei wrote:
> This patch adds a optional reset management for msdc.
> Sometimes the bootloader does not bring msdc register
> to default state, so need reset the msdc controller.
> 
> Signed-off-by: Wenbin Mei <wenbin.mei@...iatek.com>
> ---
>  drivers/mmc/host/mtk-sd.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 39e7fc54c438..2b243c03c9b2 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -22,6 +22,7 @@
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <linux/interrupt.h>
> +#include <linux/reset.h>
>  
>  #include <linux/mmc/card.h>
>  #include <linux/mmc/core.h>
> @@ -434,6 +435,7 @@ struct msdc_host {
>  	struct msdc_save_para save_para; /* used when gate HCLK */
>  	struct msdc_tune_para def_tune_para; /* default tune setting */
>  	struct msdc_tune_para saved_tune_para; /* tune result of CMD21/CMD19 */
> +	struct reset_control *reset;
>  };
>  
>  static const struct mtk_mmc_compatible mt8135_compat = {
> @@ -1516,6 +1518,12 @@ static void msdc_init_hw(struct msdc_host *host)
>  	u32 val;
>  	u32 tune_reg = host->dev_comp->pad_tune_reg;
>  
> +	if (!IS_ERR(host->reset)) {
> +		reset_control_assert(host->reset);
> +		usleep_range(10, 50);
> +		reset_control_deassert(host->reset);
> +	}
> +

This should be:

	if (host->reset) {
		reset_control_assert(host->reset);
		usleep_range(10, 50);
		reset_control_deassert(host->reset);
	}

>  	/* Configure to MMC/SD mode, clock free running */
>  	sdr_set_bits(host->base + MSDC_CFG, MSDC_CFG_MODE | MSDC_CFG_CKPDN);
>  
> @@ -2273,6 +2281,11 @@ static int msdc_drv_probe(struct platform_device *pdev)
>  	if (IS_ERR(host->src_clk_cg))
>  		host->src_clk_cg = NULL;
>  
> +	host->reset = devm_reset_control_get_optional_exclusive(&pdev->dev,
> +								"hrst");
> +	if (PTR_ERR(host->reset) == -EPROBE_DEFER)
> +		return PTR_ERR(host->reset);
> +

This should be:

	host->reset = devm_reset_control_get_optional_exclusive(&pdev->dev,
								"hrst");
	if (IS_ERR(host->reset))
		return PTR_ERR(host->reset);

If the reset is configured in DT then it should be used, even if the
reset driver is loaded later.

If the DT does not contain the reset-names = "hrst" property at all,
devm_reset_control_get_optional_*() will return NULL.

With these two changes,

Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>

regards
Philipp