Re: [PATCH 1/4] ARM STM/i.MX: Allocate memory for framebuffer during probe

[Juergen Beisert <jbe@pengutronix.de>]

Gregory CLEMENT wrote:
> With current code when the framebuffer is register, screen_base is not
> set yet. So when we want to access framebuffer from mmap we get a
> pointer to 0x0 instead of getting the pointer to the framebuffer
> address. This patch fix this bug by allocating memory for framebuffer
> during probe just before registering framebuffer driver.

Are you sure? See below

> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> ---
>  drivers/video/stm.c |   10 ++++++++++
>  1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/video/stm.c b/drivers/video/stm.c
> index f0abe4c..8a9acff 100644
> --- a/drivers/video/stm.c
> +++ b/drivers/video/stm.c
> @@ -480,6 +480,7 @@ static int stmfb_probe(struct device_d *hw_dev)
>  {
>  	struct imx_fb_videomode *pdata = hw_dev->platform_data;
>  	int ret;
> +	unsigned size;
>
>  	/* just init */
>  	fbi.info.priv = &fbi;
> @@ -497,6 +498,15 @@ static int stmfb_probe(struct device_d *hw_dev)
>  	fbi.info.yres = fbi.info.mode->yres;
>  	fbi.info.bits_per_pixel = 16;
>
> +	size = calc_line_length(fbi.info.mode->xres, fbi.info.bits_per_pixel) *
> +		fbi.info.mode->yres;
> +
> +	ret = stmfb_memory_mmgt(&fbi.info, size);
> +	if (ret != 0) {
> +		dev_err(hw_dev, "Cannot allocate framebuffer memory\n");
> +		return ret;
> +	}
> +
>  	ret = register_framebuffer(&fbi.info);
>  	if (ret != 0) {
>  		dev_err(hw_dev, "Failed to register framebuffer\n");

This probe function sets up the default mode. And register_framebuffer() 
itself calls stmfb_activate_var() which calls stmfb_memory_mmgt(). So, when 
the call to register_framebuffer() returns the 'screen_base' should no longer 
be NULL.

jbe

-- 
Pengutronix e.K.                              | Juergen Beisert             |
Linux Solutions for Science and Industry      | Phone: +49-8766-939 228     |
Vertretung Sued/Muenchen, Germany             | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686              | http://www.pengutronix.de/  |

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