[bug report] drm/amd/display: Reverted DSC programming sequence change

Dan Carpenter dan.carpenter at oracle.com
Thu Sep 15 07:42:23 UTC 2022


Hello Nagulendran, Iswara,

The patch c7783a6ed4fc: "drm/amd/display: Reverted DSC programming
sequence change" from Aug 23, 2022, leads to the following Smatch
static checker warning:

	drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link.c:4310 core_link_enable_stream()
	warn: if statement not indented

drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link.c
    4299 
    4300                 if (pipe_ctx->stream->dpms_off)
    4301                         return;
    4302 
    4303                 /* Have to setup DSC before DIG FE and BE are connected (which happens before the
    4304                  * link training). This is to make sure the bandwidth sent to DIG BE won't be
    4305                  * bigger than what the link and/or DIG BE can handle. VBID[6]/CompressedStream_flag
    4306                  * will be automatically set at a later time when the video is enabled
    4307                  * (DP_VID_STREAM_EN = 1).
    4308                  */
    4309                 if (pipe_ctx->stream->timing.flags.DSC) {
--> 4310                         if (dc_is_dp_signal(pipe_ctx->stream->signal) ||
    4311                                 dc_is_virtual_signal(pipe_ctx->stream->signal))
    4312                         dp_set_dsc_enable(pipe_ctx, true);
    4313 
    4314                 }

This seems likes a bug?  Like a line was deleted.  Or should it be:

	if (pipe_ctx->stream->timing.flags.DSC &&
            (dc_is_dp_signal(pipe_ctx->stream->signal) ||
             dc_is_virtual_signal(pipe_ctx->stream->signal)))
		dp_set_dsc_enable(pipe_ctx, true);

    4315 
    4316                 status = enable_link(state, pipe_ctx);
    4317 
    4318                 if (status != DC_OK) {
    4319                         DC_LOG_WARNING("enabling link %u failed: %d\n",
    4320                         pipe_ctx->stream->link->link_index,
    4321                         status);
    4322 
    4323                         /* Abort stream enable *unless* the failure was due to
    4324                          * DP link training - some DP monitors will recover and
    4325                          * show the stream anyway. But MST displays can't proceed

regards,
dan carpenter


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