linux-kernel - Re: [PATCH 2/2] mmc: block: Update ext_csd.cache

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Message-ID: <017e203c-e53f-b07e-fcea-e357d8947d43@intel.com>
Date:   Mon, 22 Mar 2021 20:59:04 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Avri Altman <avri.altman@....com>,
        Ulf Hansson <ulf.hansson@...aro.org>, linux-mmc@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mmc: block: Update ext_csd.cache_ctrl if it was
 written

On 22/03/21 3:36 pm, Avri Altman wrote:
> The cache function can be turned ON and OFF by writing to the CACHE_CTRL
> byte (EXT_CSD byte [33]).  However,  card->ext_csd.cache_ctrl is only
> set on init if cache size > 0.
> 
> Fix that by explicitly setting ext_csd.cache_ctrl on ext-csd write.
> 
> Signed-off-by: Avri Altman <avri.altman@....com>
> ---
>  drivers/mmc/core/block.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index a93c66aa91db..4c816d001ac1 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -571,6 +571,14 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
>  		main_md->part_curr = value & EXT_CSD_PART_CONFIG_ACC_MASK;
>  	}
>  
> +	/* Make sure to update CACHE_CTRL in case it was changed */

It might be worth noting that the cache will get turned back
on if the card is re-initialized, for example suspend/resume or
hw reset in recovery.

> +	if ((MMC_EXTRACT_INDEX_FROM_ARG(cmd.arg) == EXT_CSD_CACHE_CTRL) &&
> +	    (cmd.opcode == MMC_SWITCH)) {
> +		u8 value = MMC_EXTRACT_VALUE_FROM_ARG(cmd.arg) & 1;
> +
> +		card->ext_csd.cache_ctrl = value;
> +	}
> +
>  	/*
>  	 * According to the SD specs, some commands require a delay after
>  	 * issuing the command.
>