For DP branch devices DPCD register may define the max supported pixel rate for VGA dongles. This patch adds a check if DPCD register value is less than current setting for pixel rate.
Signed-off-by: Mika Kahola <mika.kah...@intel.com> --- drivers/gpu/drm/drm_dp_helper.c | 22 ++++++++++++++++++++++ include/drm/drm_dp_helper.h | 1 + 2 files changed, 23 insertions(+) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 2c91771..b222aa0 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -413,6 +413,28 @@ int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link) EXPORT_SYMBOL(drm_dp_link_power_down); /* + * drm_dp_max_sink_dotclock() - Compute max pixel rate + * @dotclk: reference pixel rate + * @bd: pointer to a structure containing DP branch device information + * + * Returns max supported pixel rate. + */ +int drm_dp_max_sink_dotclock(int dotclk, struct drm_dp_bd *bd) +{ + int max_dotclk = dotclk; + + /* DP to VGA dongle may define max pixel rate in DPCD */ + if (bd->present) { + if ((bd->type & DP_DS_PORT_TYPE_VGA) && + (bd->dfp.vga.dot_clk > 0)) + max_dotclk = min(dotclk, bd->dfp.vga.dot_clk); + } + + return max_dotclk; +} +EXPORT_SYMBOL(drm_dp_max_sink_dotclock); + +/* * drm_dp_bd() - read DisplayPort Receiver Capability Fields for * DP branch devices * @aux: DisplayPort AUX channel diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 831f944..ee4084d 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -882,6 +882,7 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link); int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link); int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link); int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link); +int drm_dp_max_sink_dotclock(int dotclk, struct drm_dp_bd *bd); int drm_dp_bd(struct drm_dp_aux *aux, struct drm_dp_bd *bd); int drm_dp_aux_register(struct drm_dp_aux *aux); -- 1.9.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx