On Fri, May 19, 2017 at 05:57:23PM +0800, Bibby Hsieh wrote:
> For some greater resolution, the rdma threshold
> variable will overflow.
>
> Signed-off-by: Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/mediatek/mtk_disp_rdma.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> index 0df05f9..9afdcd7 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> @@ -37,7 +37,7 @@
> #define DISP_REG_RDMA_FIFO_CON 0x0040
> #define RDMA_FIFO_UNDERFLOW_EN BIT(31)
> #define RDMA_FIFO_PSEUDO_SIZE(bytes) (((bytes) / 16) << 16)
> -#define RDMA_OUTPUT_VALID_FIFO_THRESHOLD(bytes) ((bytes) / 16)
> +#define RDMA_OUTPUT_VALID_FIFO_THRESHOLD(bytes) (((bytes) / 16) & 0x3ff)
I agree with the earlier comment; clamp_val() might be more appropriate here
and would avoid unexpected results.
>
> /**
> * struct mtk_disp_rdma - DISP_RDMA driver structure
> @@ -109,7 +109,7 @@ static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width,
> unsigned int height, unsigned int vrefresh,
> unsigned int bpc)
> {
> - unsigned int threshold;
> + unsigned long long threshold;
> unsigned int reg;
>
> rdma_update_bits(comp, DISP_REG_RDMA_SIZE_CON_0, 0xfff, width);
> @@ -121,7 +121,8 @@ static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width,
> * output threshold to 6 microseconds with 7/6 overhead to
> * account for blanking, and with a pixel depth of 4 bytes:
> */
> - threshold = width * height * vrefresh * 4 * 7 / 1000000;
> + threshold = (unsigned long long)width * height * vrefresh *
> + 4 * 7 / 1000000;
This is a 64 bit divide operation. It will result in a build failure
if compiled for a 32 bit kernel (eg arm:allmodconfig).
ERROR: "__aeabi_uldivmod" [drivers/gpu/drm/mediatek/mediatek-drm.ko] undefined!
Guenter
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