linux-kernel - Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce buffer support

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Message-ID: <aa967f6a-0526-3e33-1de7-fbe7d4264f34@nod.at>
Date:   Tue, 28 Feb 2017 22:41:11 +0100
From:   Richard Weinberger <richard@....at>
To:     Vignesh R <vigneshr@...com>, David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, Frode Isaksen <fisaksen@...libre.com>,
        linux-spi@...r.kernel.org
Subject: Re: [RFC PATCH 2/2] mtd: devices: m25p80: Enable spi-nor bounce
 buffer support

Vignesh,

Am 27.02.2017 um 13:08 schrieb Vignesh R:
> Many SPI controller drivers use DMA to read/write from m25p80 compatible
> flashes. Therefore enable bounce buffers support provided by spi-nor
> framework to take care of handling vmalloc'd buffers which may not be
> DMA'able.
> 
> Signed-off-by: Vignesh R <vigneshr@...com>
> ---
>  drivers/mtd/devices/m25p80.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index c4df3b1bded0..d05acf22eadf 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -241,6 +241,7 @@ static int m25p_probe(struct spi_device *spi)
>  	else
>  		flash_name = spi->modalias;
>  
> +	nor->flags |= SNOR_F_USE_BOUNCE_BUFFER;

Isn't there a better way to detect whether a bounce buffer is needed or not?

Thanks,
//richard