Re: [PATCH v5 5/6] drm/msm/dpu: fix error handling in dpu_rm_init

[Abhinav Kumar]

On 2/14/2022 12:43 PM, Dmitry Baryshkov wrote:

On 14/02/2022 22:15, Abhinav Kumar wrote:

On 1/21/2022 1:06 PM, Dmitry Baryshkov wrote:

Using IS_ERR_OR_NULL() together with PTR_ERR() is a typical mistake. If
the value is NULL, then the function will return 0 instead of a proper
return code. Moreover none of dpu_hw_*_init() functions can return NULL.
So, replace all dpu_rm_init()'s IS_ERR_OR_NULL() calls with IS_ERR().

Can you please give an example of a case where dpu_hw_*_init() can return NULL?

All dpu_hw_*_init() functions are only called if the corresponding
hw*_counts are valid. So I would like to understand this.

Now, if NULL is treated as a non-error case, should we atleast print
a message indicating so?

- No dpu_hw_*init() can return NULL

- If at some point any of these functions returns NULL, it will cause a premature dpu_rm_init() termination with the success (=0) status, leaving parts of RM uninitialized.

Thus I'm replacing IS_ERR_OR_NULL with IS_ERR()

Ah okay, got it.

Reviewed-by: Abhinav Kumar <quic_abhin...@quicinc.com>

Signed-off-by: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
---
  drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 12 ++++++------
  1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c

index 96554e962e38..7497538adae1 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
@@ -109,7 +109,7 @@ int dpu_rm_init(struct dpu_rm *rm,
              continue;
          }
          hw = dpu_hw_lm_init(lm->id, mmio, cat);
-        if (IS_ERR_OR_NULL(hw)) {
+        if (IS_ERR(hw)) {
              rc = PTR_ERR(hw);
              DPU_ERROR("failed lm object creation: err %d\n", rc);
              goto fail;
@@ -126,7 +126,7 @@ int dpu_rm_init(struct dpu_rm *rm,
              continue;
          }
          hw = dpu_hw_merge_3d_init(merge_3d->id, mmio, cat);
-        if (IS_ERR_OR_NULL(hw)) {
+        if (IS_ERR(hw)) {
              rc = PTR_ERR(hw);
              DPU_ERROR("failed merge_3d object creation: err %d\n",
                  rc);
@@ -144,7 +144,7 @@ int dpu_rm_init(struct dpu_rm *rm,
              continue;
          }
          hw = dpu_hw_pingpong_init(pp->id, mmio, cat);
-        if (IS_ERR_OR_NULL(hw)) {
+        if (IS_ERR(hw)) {
              rc = PTR_ERR(hw);
              DPU_ERROR("failed pingpong object creation: err %d\n",
                  rc);
@@ -168,7 +168,7 @@ int dpu_rm_init(struct dpu_rm *rm,
              continue;
          }
          hw = dpu_hw_intf_init(intf->id, mmio, cat);
-        if (IS_ERR_OR_NULL(hw)) {
+        if (IS_ERR(hw)) {
              rc = PTR_ERR(hw);
              DPU_ERROR("failed intf object creation: err %d\n", rc);
              goto fail;
@@ -185,7 +185,7 @@ int dpu_rm_init(struct dpu_rm *rm,
              continue;
          }
          hw = dpu_hw_ctl_init(ctl->id, mmio, cat);
-        if (IS_ERR_OR_NULL(hw)) {
+        if (IS_ERR(hw)) {
              rc = PTR_ERR(hw);
              DPU_ERROR("failed ctl object creation: err %d\n", rc);
              goto fail;
@@ -202,7 +202,7 @@ int dpu_rm_init(struct dpu_rm *rm,
              continue;
          }
          hw = dpu_hw_dspp_init(dspp->id, mmio, cat);
-        if (IS_ERR_OR_NULL(hw)) {
+        if (IS_ERR(hw)) {
              rc = PTR_ERR(hw);
              DPU_ERROR("failed dspp object creation: err %d\n", rc);
              goto fail;