[PATCH] drm/gma500: fix error check

[PATCH] drm/gma500: fix error check

[trix]

From: Tom Rix <trix@redhat.com>

Reviewing this block of code in cdv_intel_dp_init()

ret = cdv_intel_dp_aux_native_read(gma_encoder, DP_DPCD_REV, ...

cdv_intel_edp_panel_vdd_off(gma_encoder);
if (ret == 0) {
	/* if this fails, presume the device is a ghost */
	DRM_INFO("failed to retrieve link info, disabling eDP\n");
	drm_encoder_cleanup(encoder);
	cdv_intel_dp_destroy(connector);
	goto err_priv;
} else {

The (ret == 0) is not strict enough.
cdv_intel_dp_aux_native_read() returns > 0 on success
otherwise it is failure.

So change to <=

Fixes: d112a8163f83 ("gma500/cdv: Add eDP support")

Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/gpu/drm/gma500/cdv_intel_dp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/gma500/cdv_intel_dp.c b/drivers/gpu/drm/gma500/cdv_intel_dp.c
index f41cbb753bb4..720a767118c9 100644
--- a/drivers/gpu/drm/gma500/cdv_intel_dp.c
+++ b/drivers/gpu/drm/gma500/cdv_intel_dp.c
@@ -2078,7 +2078,7 @@ cdv_intel_dp_init(struct drm_device *dev, struct psb_intel_mode_device *mode_dev
 					       intel_dp->dpcd,
 					       sizeof(intel_dp->dpcd));
 		cdv_intel_edp_panel_vdd_off(gma_encoder);
-		if (ret == 0) {
+		if (ret <= 0) {
 			/* if this fails, presume the device is a ghost */
 			DRM_INFO("failed to retrieve link info, disabling eDP\n");
 			drm_encoder_cleanup(encoder);
-- 
2.18.1

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Re: [PATCH] drm/gma500: fix error check

[Patrik Jakobsson]

On Wed, Aug 5, 2020 at 10:59 PM <trix@redhat.com> wrote:
>
> From: Tom Rix <trix@redhat.com>
>
> Reviewing this block of code in cdv_intel_dp_init()
>
> ret = cdv_intel_dp_aux_native_read(gma_encoder, DP_DPCD_REV, ...
>
> cdv_intel_edp_panel_vdd_off(gma_encoder);
> if (ret == 0) {
>         /* if this fails, presume the device is a ghost */
>         DRM_INFO("failed to retrieve link info, disabling eDP\n");
>         drm_encoder_cleanup(encoder);
>         cdv_intel_dp_destroy(connector);
>         goto err_priv;
> } else {
>
> The (ret == 0) is not strict enough.
> cdv_intel_dp_aux_native_read() returns > 0 on success
> otherwise it is failure.
>
> So change to <=

Thanks for the patch. Looks correct.

Will apply to drm-misc-next

-Patrik

>
> Fixes: d112a8163f83 ("gma500/cdv: Add eDP support")
>
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
>  drivers/gpu/drm/gma500/cdv_intel_dp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/gma500/cdv_intel_dp.c b/drivers/gpu/drm/gma500/cdv_intel_dp.c
> index f41cbb753bb4..720a767118c9 100644
> --- a/drivers/gpu/drm/gma500/cdv_intel_dp.c
> +++ b/drivers/gpu/drm/gma500/cdv_intel_dp.c
> @@ -2078,7 +2078,7 @@ cdv_intel_dp_init(struct drm_device *dev, struct psb_intel_mode_device *mode_dev
>                                                intel_dp->dpcd,
>                                                sizeof(intel_dp->dpcd));
>                 cdv_intel_edp_panel_vdd_off(gma_encoder);
> -               if (ret == 0) {
> +               if (ret <= 0) {
>                         /* if this fails, presume the device is a ghost */
>                         DRM_INFO("failed to retrieve link info, disabling eDP\n");
>                         drm_encoder_cleanup(encoder);
> --
> 2.18.1
>
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