Hi,
> -----Original Message-----
> From: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Sent: Wednesday, July 5, 2023 12:50 AM
> To: javierm@xxxxxxxxxx; maarten.lankhorst@xxxxxxxxxxxxxxx;
> mripard@xxxxxxxxxx
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-samsung-soc@xxxxxxxxxxxxxxx; linux-tegra@xxxxxxxxxxxxxxx; linux-
> fbdev@xxxxxxxxxxxxxxx; Thomas Zimmermann <tzimmermann@xxxxxxx>; Inki Dae
> <inki.dae@xxxxxxxxxxx>; Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx>; Kyungmin
> Park <kyungmin.park@xxxxxxxxxxx>; Krzysztof Kozlowski
> <krzysztof.kozlowski@xxxxxxxxxx>; Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
> Subject: [PATCH 05/10] drm/exynos: Use fbdev DMA helpers
>
> Use fbdev's DMA helpers for fbdev emulation. They drivers previously
> used the I/O-memory helpers, while allocating DMA-able system memory.
> This could (in theory) result in bus errors from accessing the memory
> range.
>
> This bug has been present since the exynos driver was first added.
Acked-by : Inki Dae <inki.dae@xxxxxxxxxxx>
Thanks,
Inki Dae
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Fixes: 1c248b7d2960 ("DRM: add DRM Driver for Samsung SoC EXYNOS4210.")
> Cc: Inki Dae <inki.dae@xxxxxxxxxxx>
> Cc: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx>
> Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> Cc: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/exynos/Kconfig | 2 +-
> drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 4 ++--
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/Kconfig
> b/drivers/gpu/drm/exynos/Kconfig
> index 7ca7e1dab52c..661b42ad4873 100644
> --- a/drivers/gpu/drm/exynos/Kconfig
> +++ b/drivers/gpu/drm/exynos/Kconfig
> @@ -7,7 +7,7 @@ config DRM_EXYNOS
> select DRM_DISPLAY_HELPER if DRM_EXYNOS_DP
> select DRM_KMS_HELPER
> select VIDEOMODE_HELPERS
> - select FB_IO_HELPERS if DRM_FBDEV_EMULATION
> + select FB_DMA_HELPERS if DRM_FBDEV_EMULATION
> select SND_SOC_HDMI_CODEC if SND_SOC
> help
> Choose this option if you have a Samsung SoC Exynos chipset.
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> index fdf65587f1fe..7ca3424b59ce 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> @@ -49,9 +49,9 @@ static void exynos_drm_fb_destroy(struct fb_info *info)
>
> static const struct fb_ops exynos_drm_fb_ops = {
> .owner = THIS_MODULE,
> - __FB_DEFAULT_IO_OPS_RDWR,
> + __FB_DEFAULT_DMA_OPS_RDWR,
> DRM_FB_HELPER_DEFAULT_OPS,
> - __FB_DEFAULT_IO_OPS_DRAW,
> + __FB_DEFAULT_DMA_OPS_DRAW,
> .fb_mmap = exynos_drm_fb_mmap,
> .fb_destroy = exynos_drm_fb_destroy,
> };
> --
> 2.41.0
