DC can turn off the display clock when no displays are connected or when all displays are off, for reference see: - dce*_validate_bandwidth
DC also assumes that the DP clock is always on and never powers it down, for reference see: - dce110_clock_source_power_down In case of DCE 6.0 and 6.4, PLL0 is the clock source for both the engine clock and DP clock, for reference see: - radeon_atom_pick_pll - atombios_crtc_set_disp_eng_pll Therefore, PLL0 should be always kept running on DCE 6.0 and 6.4. This commit achieves that by ensuring that by setting the display clock to the corresponding value in low power state instead of zero. This fixes a page flip timeout on SI with DC which happens when all connected displays are blanked. Signed-off-by: Timur Kristóf <timur.kris...@gmail.com> --- .../amd/display/dc/resource/dce60/dce60_resource.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c index 53b60044653f..c164d2500c2a 100644 --- a/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c +++ b/drivers/gpu/drm/amd/display/dc/resource/dce60/dce60_resource.c @@ -881,7 +881,16 @@ static enum dc_status dce60_validate_bandwidth( context->bw_ctx.bw.dce.dispclk_khz = 681000; context->bw_ctx.bw.dce.yclk_khz = 250000 * MEMORY_TYPE_MULTIPLIER_CZ; } else { - context->bw_ctx.bw.dce.dispclk_khz = 0; + /* On DCE 6.0 and 6.4 the PLL0 is both the display engine clock and + * the DP clock, and shouldn't be turned off. Just select the display + * clock value from its low power mode. + */ + if (dc->ctx->dce_version == DCE_VERSION_6_0 || + dc->ctx->dce_version == DCE_VERSION_6_4) + context->bw_ctx.bw.dce.dispclk_khz = 352000; + else + context->bw_ctx.bw.dce.dispclk_khz = 0; + context->bw_ctx.bw.dce.yclk_khz = 0; } -- 2.50.1