[PATCH] drm/msm/dp: use ARRAY_SIZE for calculating num_descs

[Kuogee Hsieh]

On 6/27/2022 9:54 AM, Dmitry Baryshkov wrote:
> If for some reason the msm_dp_config::descs array starts from non-zero
> index or contains the hole, setting the msm_dp_config::num_descs might
> be not that obvious and error-prone. Use ARRAY_SIZE to set this field
> rather than encoding the value manually.
>
> Reported-by: Kuogee Hsieh <quic_khsieh at quicinc.com>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> ---
>   drivers/gpu/drm/msm/dp/dp_display.c | 46 +++++++++++++++++------------
>   1 file changed, 27 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index f87fa3ba1e25..6fed738a9467 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -131,35 +131,43 @@ struct msm_dp_config {
>   	size_t num_descs;
>   };
>   
> +static const struct msm_dp_desc sc7180_dp_descs[] = {
> +	[MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
> +};
> +
>   static const struct msm_dp_config sc7180_dp_cfg = {
> -	.descs = (const struct msm_dp_desc[]) {
> -		[MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
> -	},
> -	.num_descs = 1,
> +	.descs = sc7180_dp_descs,
> +	.num_descs = ARRAY_SIZE(sc7180_dp_descs),
> +};
> +

why you want to do that?

It is very clear only one entry, why you want to make it 2 entry here?

can you just embedded MSM_DP_COTROLLER_x into struct msm_dp_config?

> +static const struct msm_dp_desc sc7280_dp_descs[] = {
> +	[MSM_DP_CONTROLLER_0] =	{ .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort, .wide_bus_en = true },
> +	[MSM_DP_CONTROLLER_1] =	{ .io_start = 0x0aea0000, .connector_type = DRM_MODE_CONNECTOR_eDP, .wide_bus_en = true },
>   };
>   
>   static const struct msm_dp_config sc7280_dp_cfg = {
> -	.descs = (const struct msm_dp_desc[]) {
> -		[MSM_DP_CONTROLLER_0] =	{ .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort, .wide_bus_en = true },
> -		[MSM_DP_CONTROLLER_1] =	{ .io_start = 0x0aea0000, .connector_type = DRM_MODE_CONNECTOR_eDP, .wide_bus_en = true },
> -	},
> -	.num_descs = 2,
> +	.descs = sc7280_dp_descs,
> +	.num_descs = ARRAY_SIZE(sc7280_dp_descs),
> +};
> +
> +static const struct msm_dp_desc sc8180x_dp_descs[] = {
> +	[MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
> +	[MSM_DP_CONTROLLER_1] = { .io_start = 0x0ae98000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
> +	[MSM_DP_CONTROLLER_2] = { .io_start = 0x0ae9a000, .connector_type = DRM_MODE_CONNECTOR_eDP },
>   };
>   
>   static const struct msm_dp_config sc8180x_dp_cfg = {
> -	.descs = (const struct msm_dp_desc[]) {
> -		[MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
> -		[MSM_DP_CONTROLLER_1] = { .io_start = 0x0ae98000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
> -		[MSM_DP_CONTROLLER_2] = { .io_start = 0x0ae9a000, .connector_type = DRM_MODE_CONNECTOR_eDP },
> -	},
> -	.num_descs = 3,
> +	.descs = sc8180x_dp_descs,
> +	.num_descs = ARRAY_SIZE(sc8180x_dp_descs),
> +};
> +
> +static const struct msm_dp_desc sm8350_dp_descs[] = {
> +	[MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
>   };
>   
>   static const struct msm_dp_config sm8350_dp_cfg = {
> -	.descs = (const struct msm_dp_desc[]) {
> -		[MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000, .connector_type = DRM_MODE_CONNECTOR_DisplayPort },
> -	},
> -	.num_descs = 1,
> +	.descs = sm8350_dp_descs,
> +	.num_descs = ARRAY_SIZE(sm8350_dp_descs),
>   };
>   
>   static const struct of_device_id dp_dt_match[] = {