linux-kernel - Re: [PATCH] staging: fbtft: do not allocate huge txbuf

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Message-ID: <8dfb88dd-ee33-349d-200e-ff5619f872bb@tronnes.org>
Date:	Thu, 9 Jun 2016 18:20:17 +0200
From:	Noralf Trønnes <noralf@...nnes.org>
To:	Michal Suchanek <hramrach@...il.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: fbtft: do not allocate huge txbuf


Den 09.06.2016 17:08, skrev Michal Suchanek:
> txbuflen can be set to arbitrary value by user and it is also set
> automagically to the maximum transfer size of the SPI master controller.

AFAICT this is a result of your previous patch. Please make a new version of
your previous patch with this fix in it. Also make a note in that thread 
that
a new version is made so Greg doesn't pull it when he sees my ack. He
handles a large volume of patches so let's make it as easy as we can for 
him.

Thanks,
Noralf.

> Do not allocate the buffer when larger than vmem. When my SPI master
> controller reports maximum transfer size 16M the probe of fbtft fails.
>
> Signed-off-by: Michal Suchanek <hramrach@...il.com>
> ---
>   drivers/staging/fbtft/fbtft-core.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> index f3bdc8f..b95cf69 100644
> --- a/drivers/staging/fbtft/fbtft-core.c
> +++ b/drivers/staging/fbtft/fbtft-core.c
> @@ -820,6 +820,8 @@ struct fb_info *fbtft_framebuffer_alloc(struct fbtft_display *display,
>   	/* Transmit buffer */
>   	if (txbuflen == -1)
>   		txbuflen = vmem_size + 2; /* add in case startbyte is used */
> +	if (txbuflen >= vmem_size + 2)
> +		txbuflen = 0;
>   
>   #ifdef __LITTLE_ENDIAN
>   	if ((!txbuflen) && (bpp > 8))