| Message ID | 20211112112433.942075-1-hsinyi@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/bridge: anx7625: Fix edid_read break case in sp_tx_edid_read() | expand |
Hey Hsin-Yi, Thanks for catching this. checkpatch --strict is throwing an error for this patch. With that, feel free to add my r-b. Reviewed-by: Robert Foss <robert.foss@linaro.org> On Fri, 12 Nov 2021 at 12:24, Hsin-Yi Wang <hsinyi@chromium.org> wrote: > > edid_read() was assumed to return 0 on success. After > 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()"), > the function can return >= 0 for successful case. Fix the g_edid_break > condition in sp_tx_edid_read(). > > Fixes: 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()") > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org> > --- > drivers/gpu/drm/bridge/analogix/anx7625.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c > index 1a871f6b6822ee..392203b576042b 100644 > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c > @@ -826,7 +826,7 @@ static int sp_tx_edid_read(struct anx7625_data *ctx, > g_edid_break = edid_read(ctx, offset, > pblock_buf); > > - if (g_edid_break) > + if (g_edid_break < 0) > break; > > memcpy(&pedid_blocks_buf[offset], > -- > 2.34.0.rc1.387.gb447b232ab-goog >
On Fri, Nov 12, 2021 at 07:24:33PM +0800, Hsin-Yi Wang wrote: > edid_read() was assumed to return 0 on success. After > 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()"), > the function can return >= 0 for successful case. Fix the g_edid_break > condition in sp_tx_edid_read(). > > Fixes: 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()") > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org> > Reviewed-by: Robert Foss <robert.foss@linaro.org> > --- > drivers/gpu/drm/bridge/analogix/anx7625.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c > index 1a871f6b6822ee..392203b576042b 100644 > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c > @@ -826,7 +826,7 @@ static int sp_tx_edid_read(struct anx7625_data *ctx, > g_edid_break = edid_read(ctx, offset, > pblock_buf); > > - if (g_edid_break) > + if (g_edid_break < 0) > break; g_edid_break is declared u8 and thus never < 0. The break; statement doesn't indicate an error but that a break was encountered, and the value of g_edid_break == 1 is used elsewhere in the function to indicate that condition. It also doesn't break out of the outer loop, but only out of the switch statement. With this patch in place, g_edid_break will have a more or less random value after an error, and the behavior of this function will be undefined. Guenter
On Fri, Nov 19, 2021 at 12:52 AM Guenter Roeck <linux@roeck-us.net> wrote: > > On Fri, Nov 12, 2021 at 07:24:33PM +0800, Hsin-Yi Wang wrote: > > edid_read() was assumed to return 0 on success. After > > 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()"), > > the function can return >= 0 for successful case. Fix the g_edid_break > > condition in sp_tx_edid_read(). > > > > Fixes: 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()") > > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org> > > Reviewed-by: Robert Foss <robert.foss@linaro.org> > > --- > > drivers/gpu/drm/bridge/analogix/anx7625.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c > > index 1a871f6b6822ee..392203b576042b 100644 > > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c > > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c > > @@ -826,7 +826,7 @@ static int sp_tx_edid_read(struct anx7625_data *ctx, > > g_edid_break = edid_read(ctx, offset, > > pblock_buf); > > > > - if (g_edid_break) > > + if (g_edid_break < 0) > > break; > > g_edid_break is declared u8 and thus never < 0. The break; statement > doesn't indicate an error but that a break was encountered, and the > value of g_edid_break == 1 is used elsewhere in the function to indicate > that condition. It also doesn't break out of the outer loop, but only > out of the switch statement. > > With this patch in place, g_edid_break will have a more or less random > value after an error, and the behavior of this function will be undefined. > Before 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()"), edid_read() only returns 0 (i2c read bytes > 0) or -EIO, so g_edid_break also couldn't be 1. After checking the code more, I guess what it wants to do is: - For the 1st and 2nd block (case 0 and 1) in sp_tx_edid_read(), copy the buffer on success. - For other blocks (case 2 and 3), process the buffer when the last g_edid_break updated in previous blocks is not 1. These blocks probably don't need to be updated if previous blocks have failed. The whole edid will be checked if valid. I will update the patch. > Guenter
diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c index 1a871f6b6822ee..392203b576042b 100644 --- a/drivers/gpu/drm/bridge/analogix/anx7625.c +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c @@ -826,7 +826,7 @@ static int sp_tx_edid_read(struct anx7625_data *ctx, g_edid_break = edid_read(ctx, offset, pblock_buf); - if (g_edid_break) + if (g_edid_break < 0) break; memcpy(&pedid_blocks_buf[offset],
edid_read() was assumed to return 0 on success. After 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()"), the function can return >= 0 for successful case. Fix the g_edid_break condition in sp_tx_edid_read(). Fixes: 7f16d0f3b8e2("drm/bridge: anx7625: Propagate errors from sp_tx_rst_aux()") Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org> --- drivers/gpu/drm/bridge/analogix/anx7625.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)