linux-kernel - Re: [PATCH] OMAP: HSMMC: Do not enable buffer ready interrupt if using DMA

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Message-ID: <20090428213833.18afbba0@mjolnir.ossman.eu>
Date:	Tue, 28 Apr 2009 21:38:33 +0200
From:	Pierre Ossman <pierre@...man.eu>
To:	Jarkko Lavinen <jarkko.lavinen@...ia.com>,
	Tony Lindgren <tony@...mide.com>
Cc:	"Gadiyar, Anand" <gadiyar@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
Subject: Re: [PATCH] OMAP: HSMMC: Do not enable buffer ready interrupt if
 using DMA

Jarkko? Tony?

On Tue, 21 Apr 2009 13:09:22 +0530
"Gadiyar, Anand" <gadiyar@...com> wrote:

> From: Anand Gadiyar <gadiyar@...com>
> 
> OMAP: HSMMC: Do not enable buffer ready interrupt if using DMA
> 
> This considerably reduces the number of interrupts during a transfer
> and ought to result in some power saving.
> 
> Signed-off-by: Anand Gadiyar <gadiyar@...com>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>
> Acked-by: Kishore Kadiyala <kishore.kadiyala@...com>
> ---
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index e62a22a..2d83807 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -70,6 +70,8 @@
>  #define DTO_MASK		0x000F0000
>  #define DTO_SHIFT		16
>  #define INT_EN_MASK		0x307F0033
> +#define BWR_ENABLE		(1 << 4)
> +#define BRR_ENABLE		(1 << 5)
>  #define INIT_STREAM		(1 << 1)
>  #define DP_SELECT		(1 << 21)
>  #define DDIR			(1 << 4)
> @@ -241,7 +243,12 @@ mmc_omap_start_command(struct mmc_omap_host *host, struct mmc_command *cmd,
>  	 */
>  	OMAP_HSMMC_WRITE(host->base, STAT, STAT_CLEAR);
>  	OMAP_HSMMC_WRITE(host->base, ISE, INT_EN_MASK);
> -	OMAP_HSMMC_WRITE(host->base, IE, INT_EN_MASK);
> +
> +	if (host->use_dma)
> +		OMAP_HSMMC_WRITE(host->base, IE,
> +				 INT_EN_MASK & ~(BRR_ENABLE | BWR_ENABLE));
> +	else
> +		OMAP_HSMMC_WRITE(host->base, IE, INT_EN_MASK);
>  
>  	host->response_busy = 0;
>  	if (cmd->flags & MMC_RSP_PRESENT) {


-- 
     -- Pierre Ossman

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