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Date:   Mon, 20 Apr 2020 12:15:18 -0700
From:   Matthias Kaehlcke <mka@chromium.org>
To:     Yong Mao <yong.mao@mediatek.com>
Cc:     Ulf Hansson <ulf.hansson@linaro.org>,
        Chaotian Jing <chaotian.jing@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        srv_heupstream@mediatek.com
Subject: Re: [PATCH 1/3] mmc: core: need do mmc_power_cycle in
 mmc_sdio_resend_if_cond
Message-ID: <20200420191518.GG199755@google.com>
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 <1586835611-13857-2-git-send-email-yong.mao@mediatek.com>
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Hi,

On Tue, Apr 14, 2020 at 11:40:09AM +0800, Yong Mao wrote:
> From: yong mao <yong.mao@mediatek.com>
> 
> When mmc_sdio_resned_if_cond is invoked, it indicates the SDIO
> device is not in the right state. In this condition, the previous
> implementation of mmc_sdio_resend_if_cond can't make sure SDIO
> device be back to idle state. mmc_power_cycle can reset the SDIO
> device by HW and also make sure SDIO device enter to idle state
> correctly.
> 
> Signed-off-by: Yong Mao <yong.mao@mediatek.com>
> ---
>  drivers/mmc/core/sdio.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
> index ebb387a..ada0a80 100644
> --- a/drivers/mmc/core/sdio.c
> +++ b/drivers/mmc/core/sdio.c
> @@ -546,6 +546,7 @@ static int mmc_sdio_init_uhs_card(struct mmc_card *card)
>  static void mmc_sdio_resend_if_cond(struct mmc_host *host,
>  				    struct mmc_card *card)
>  {
> +	mmc_power_cycle(host, host->card->ocr);

My MMC/SDIO background is limited, but it seems this isn't needed for the
vast majority of SDIO devices, otherwise it probably would have been added
earlier. I wonder if it would make sense to make the power cycle
conditional through a quirk, to limit it to the devices that need it.

>  	sdio_reset(host);
>  	mmc_go_idle(host);
>  	mmc_send_if_cond(host, host->ocr_avail);
> -- 
> 1.9.1