Am Freitag, den 26.08.2016, 16:30 +0200 schrieb Marek Vasut:
> Allocate the framebuffer memory as coherent, otherwise the framebuffer
> will suffer from artifacts when displaying scrolling text or video.
> This can be replicated on i.MX6SX (armv7), which has more complex memory
> architecture compared to the i.MX23/28 (armv5).
>
> Signed-off-by: Marek Vasut <marex@xxxxxxx>
> Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> Cc: Fabio Estevam <fabio.estevam@xxxxxxx>
> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> ---
> drivers/video/fbdev/mxsfb.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/video/fbdev/mxsfb.c b/drivers/video/fbdev/mxsfb.c
> index 4e6608c..bd1a310 100644
> --- a/drivers/video/fbdev/mxsfb.c
> +++ b/drivers/video/fbdev/mxsfb.c
> @@ -800,6 +800,7 @@ static int mxsfb_init_fbinfo(struct mxsfb_info *host,
> struct fb_videomode *vmode)
> {
> int ret;
> + struct device *dev = &host->pdev->dev;
> struct fb_info *fb_info = &host->fb_info;
> struct fb_var_screeninfo *var = &fb_info->var;
> dma_addr_t fb_phys;
> @@ -825,12 +826,11 @@ static int mxsfb_init_fbinfo(struct mxsfb_info *host,
>
> /* Memory allocation for framebuffer */
> fb_size = SZ_2M;
> - fb_virt = alloc_pages_exact(fb_size, GFP_DMA);
> + fb_virt = dma_alloc_coherent(dev, PAGE_ALIGN(fb_size), &fb_phys,
> + GFP_KERNEL);
You probably want writecombined memory here instead of coherent. Using
coherent memory for framebuffers sucks performance wise.
> if (!fb_virt)
> return -ENOMEM;
>
> - fb_phys = virt_to_phys(fb_virt);
> -
> fb_info->fix.smem_start = fb_phys;
> fb_info->screen_base = fb_virt;
> fb_info->screen_size = fb_info->fix.smem_len = fb_size;
> @@ -843,9 +843,11 @@ static int mxsfb_init_fbinfo(struct mxsfb_info *host,
>
> static void mxsfb_free_videomem(struct mxsfb_info *host)
> {
> + struct device *dev = &host->pdev->dev;
> struct fb_info *fb_info = &host->fb_info;
>
> - free_pages_exact(fb_info->screen_base, fb_info->fix.smem_len);
> + dma_free_coherent(dev, fb_info->screen_size, fb_info->screen_base,
> + fb_info->fix.smem_start);
> }
>
> static const struct platform_device_id mxsfb_devtype[] = {
--
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