diff options
Diffstat (limited to 'drm-vc4-Fix-HDMI-mode-validation.patch')
| -rw-r--r-- | drm-vc4-Fix-HDMI-mode-validation.patch | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/drm-vc4-Fix-HDMI-mode-validation.patch b/drm-vc4-Fix-HDMI-mode-validation.patch new file mode 100644 index 000000000..224c8fa27 --- /dev/null +++ b/drm-vc4-Fix-HDMI-mode-validation.patch @@ -0,0 +1,65 @@ +From patchwork Thu Mar 26 12:20:01 2020 +Content-Type: text/plain; charset="utf-8" +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Subject: drm/vc4: Fix HDMI mode validation +From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> +X-Patchwork-Id: 358980 +Message-Id: <20200326122001.22215-1-nsaenzjulienne@suse.de> +To: Eric Anholt <eric@anholt.net>, + Daniel Vetter <daniel.vetter@ffwll.ch> +Cc: Stefan Wahren <stefan.wahren@i2se.com>, f.fainelli@gmail.com, + Dave Stevenson <dave.stevenson@raspberrypi.com>, + David Airlie <airlied@linux.ie>, linux-kernel@vger.kernel.org, + dri-devel@lists.freedesktop.org, maxime@cerno.tech, + Nicolas Saenz Julienne <nsaenzjulienne@suse.de>, + linux-rpi-kernel@lists.infradead.org +Date: Thu, 26 Mar 2020 13:20:01 +0100 + +Current mode validation impedes setting up some video modes which should +be supported otherwise. Namely 1920x1200@60Hz. + +Fix this by lowering the minimum HDMI state machine clock to pixel clock +ratio allowed. + +Fixes: 32e823c63e90 ("drm/vc4: Reject HDMI modes with too high of clocks") +Reported-by: Stefan Wahren <stefan.wahren@i2se.com> +Suggested-by: Dave Stevenson <dave.stevenson@raspberrypi.com> +Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> +Reviewed-by: Maxime Ripard <mripard@kernel.org> +--- + drivers/gpu/drm/vc4/vc4_hdmi.c | 20 ++++++++++++++++---- + 1 file changed, 16 insertions(+), 4 deletions(-) + +diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c +index cea18dc15f77..340719238753 100644 +--- a/drivers/gpu/drm/vc4/vc4_hdmi.c ++++ b/drivers/gpu/drm/vc4/vc4_hdmi.c +@@ -681,11 +681,23 @@ static enum drm_mode_status + vc4_hdmi_encoder_mode_valid(struct drm_encoder *crtc, + const struct drm_display_mode *mode) + { +- /* HSM clock must be 108% of the pixel clock. Additionally, +- * the AXI clock needs to be at least 25% of pixel clock, but +- * HSM ends up being the limiting factor. ++ /* ++ * As stated in RPi's vc4 firmware "HDMI state machine (HSM) clock must ++ * be faster than pixel clock, infinitesimally faster, tested in ++ * simulation. Otherwise, exact value is unimportant for HDMI ++ * operation." This conflicts with bcm2835's vc4 documentation, which ++ * states HSM's clock has to be at least 108% of the pixel clock. ++ * ++ * Real life tests reveal that vc4's firmware statement holds up, and ++ * users are able to use pixel clocks closer to HSM's, namely for ++ * 1920x1200@60Hz. So it was decided to have leave a 1% margin between ++ * both clocks. Which, for RPi0-3 implies a maximum pixel clock of ++ * 162MHz. ++ * ++ * Additionally, the AXI clock needs to be at least 25% of ++ * pixel clock, but HSM ends up being the limiting factor. + */ +- if (mode->clock > HSM_CLOCK_FREQ / (1000 * 108 / 100)) ++ if (mode->clock > HSM_CLOCK_FREQ / (1000 * 101 / 100)) + return MODE_CLOCK_HIGH; + + return MODE_OK; |