From 9fa1d7e60ad5ad2f7859ea8912d7b0b57821a5b7 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Thu, 29 Oct 2020 14:40:17 +0100 Subject: drm/vc4: hdmi: Disable Wifi Frequencies There's cross-talk on the RPi4 between the 2.4GHz channels used by the WiFi chip and some resolutions, most notably 1440p at 60Hz. In such a case, we can either reject entirely the mode, or lower slightly the pixel frequency to remove the overlap. Let's go for the latter. Signed-off-by: Maxime Ripard Acked-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20201029134018.1948636-2-maxime@cerno.tech --- drivers/gpu/drm/vc4/vc4_hdmi.c | 21 +++++++++++++++++++++ drivers/gpu/drm/vc4/vc4_hdmi.h | 8 ++++++++ 2 files changed, 29 insertions(+) diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 4689a7338ac5..afc178b0d89f 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -760,6 +760,9 @@ static void vc4_hdmi_encoder_enable(struct drm_encoder *encoder) { } +#define WIFI_2_4GHz_CH1_MIN_FREQ 2400000000ULL +#define WIFI_2_4GHz_CH1_MAX_FREQ 2422000000ULL + static int vc4_hdmi_encoder_atomic_check(struct drm_encoder *encoder, struct drm_crtc_state *crtc_state, struct drm_connector_state *conn_state) @@ -767,12 +770,27 @@ static int vc4_hdmi_encoder_atomic_check(struct drm_encoder *encoder, struct drm_display_mode *mode = &crtc_state->adjusted_mode; struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder); unsigned long long pixel_rate = mode->clock * 1000; + unsigned long long tmds_rate; if (vc4_hdmi->variant->unsupported_odd_h_timings && ((mode->hdisplay % 2) || (mode->hsync_start % 2) || (mode->hsync_end % 2) || (mode->htotal % 2))) return -EINVAL; + /* + * The 1440p@60 pixel rate is in the same range than the first + * WiFi channel (between 2.4GHz and 2.422GHz with 22MHz + * bandwidth). Slightly lower the frequency to bring it out of + * the WiFi range. + */ + tmds_rate = pixel_rate * 10; + if (vc4_hdmi->disable_wifi_frequencies && + (tmds_rate >= WIFI_2_4GHz_CH1_MIN_FREQ && + tmds_rate <= WIFI_2_4GHz_CH1_MAX_FREQ)) { + mode->clock = 238560; + pixel_rate = mode->clock * 1000; + } + if (pixel_rate > vc4_hdmi->variant->max_pixel_clock) return -EINVAL; @@ -1719,6 +1737,9 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data) vc4_hdmi->hpd_active_low = hpd_gpio_flags & OF_GPIO_ACTIVE_LOW; } + vc4_hdmi->disable_wifi_frequencies = + of_property_read_bool(dev->of_node, "wifi-2.4ghz-coexistence"); + pm_runtime_enable(dev); drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_TMDS); diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h index 6815e93b1a48..0526a9cf608a 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.h +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h @@ -142,6 +142,14 @@ struct vc4_hdmi { int hpd_gpio; bool hpd_active_low; + /* + * On some systems (like the RPi4), some modes are in the same + * frequency range than the WiFi channels (1440p@60Hz for + * example). Should we take evasive actions because that system + * has a wifi adapter? + */ + bool disable_wifi_frequencies; + struct cec_adapter *cec_adap; struct cec_msg cec_rx_msg; bool cec_tx_ok; -- cgit v1.2.3