linux-kernel - Re: [PATCH 2/3] mmc: dw_mmc: simplify the SDMMC_CLKEN_LOW

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Message-id: <55D13F07.70309@samsung.com>
Date:	Mon, 17 Aug 2015 10:55:19 +0900
From:	Jaehoon Chung <jh80.chung@...sung.com>
To:	Michal Suchanek <hramrach@...il.com>, linux-sunxi@...glegroups.com,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	David Lanzendörfer 
	<david.lanzendoerfer@....ch>, Hans de Goede <hdegoede@...hat.com>,
	Chen-Yu Tsai <wens@...e.org>, Arnd Bergmann <arnd@...db.de>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3] mmc: dw_mmc: simplify the SDMMC_CLKEN_LOW_PWR logic

Hi, Michal.

On 08/12/2015 09:23 PM, Michal Suchanek wrote:
> The driver has open-coded test for SDIO cards. Use the mmc core provided
> MMC_QUIRK_BROKEN_CLK_GATING flag instead.

Did you use the clock-gating for SDIO cards?
Doesn't MMC_CAP_SDIO_IRQ bit set? Which case is broken?
Could you explain to me more?

Best Regards,
Jaehoon Chung

> 
> As a bonus this may enable clock gating on SDIO cards that are known to
> work with it.
> 
> Signed-off-by: Michal Suchanek <hramrach@...il.com>
> ---
>  drivers/mmc/host/dw_mmc.c | 33 +++++++++++++++------------------
>  1 file changed, 15 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 40e9d8e..3bc9fd7 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1335,27 +1335,24 @@ static void dw_mci_init_card(struct mmc_host *mmc, struct mmc_card *card)
>  	 * description of the CLKENA register we should disable low power mode
>  	 * for SDIO cards if we need SDIO interrupts to work.
>  	 */
> -	if (mmc->caps & MMC_CAP_SDIO_IRQ) {
> -		const u32 clken_low_pwr = SDMMC_CLKEN_LOW_PWR << slot->id;
> -		u32 clk_en_a_old;
> -		u32 clk_en_a;
> +	const u32 clken_low_pwr = SDMMC_CLKEN_LOW_PWR << slot->id;
> +	u32 clk_en_a_old;
> +	u32 clk_en_a;
>  
> -		clk_en_a_old = mci_readl(host, CLKENA);
> +	clk_en_a_old = mci_readl(host, CLKENA);
>  
> -		if (card->type == MMC_TYPE_SDIO ||
> -		    card->type == MMC_TYPE_SD_COMBO) {
> -			set_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags);
> -			clk_en_a = clk_en_a_old & ~clken_low_pwr;
> -		} else {
> -			clear_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags);
> -			clk_en_a = clk_en_a_old | clken_low_pwr;
> -		}
> +	if (card->quirks & MMC_QUIRK_BROKEN_CLK_GATING) {
> +		set_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags);
> +		clk_en_a = clk_en_a_old & ~clken_low_pwr;
> +	} else {
> +		clear_bit(DW_MMC_CARD_NO_LOW_PWR, &slot->flags);
> +		clk_en_a = clk_en_a_old | clken_low_pwr;
> +	}
>  
> -		if (clk_en_a != clk_en_a_old) {
> -			mci_writel(host, CLKENA, clk_en_a);
> -			mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
> -				     SDMMC_CMD_PRV_DAT_WAIT, 0);
> -		}
> +	if (clk_en_a != clk_en_a_old) {
> +		mci_writel(host, CLKENA, clk_en_a);
> +		mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
> +				SDMMC_CMD_PRV_DAT_WAIT, 0);
>  	}
>  }
>  
> 

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