From: Douglas Anderson <dianders@chromium.org>
To: Andrzej Hajda <a.hajda@samsung.com>,
Neil Armstrong <narmstrong@baylibre.com>
Cc: robdclark@chromium.org, linux-arm-msm@vger.kernel.org,
bjorn.andersson@linaro.org, seanpaul@chromium.org,
Jeffrey Hugo <jeffrey.l.hugo@gmail.com>,
Daniel Vetter <daniel@ffwll.ch>,
Douglas Anderson <dianders@chromium.org>,
Rob Clark <robdclark@gmail.com>, Jonas Karlman <jonas@kwiboo.se>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
David Airlie <airlied@linux.ie>,
Jernej Skrabec <jernej.skrabec@siol.net>,
Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Subject: [PATCH v3 5/9] drm/bridge: ti-sn65dsi86: Read num lanes from the DP sink
Date: Wed, 18 Dec 2019 14:35:26 -0800 [thread overview]
Message-ID: <20191218143416.v3.5.Idbd0051d0de53f7e9d18a291ea33011c0854fcc6@changeid> (raw)
In-Reply-To: <20191218223530.253106-1-dianders@chromium.org>
At least one panel hooked up to the bridge (AUO B116XAK01) only
supports 1 lane of DP. Let's read this information and stop
hardcoding 4 DP lanes.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
---
Changes in v3: None
Changes in v2: None
drivers/gpu/drm/bridge/ti-sn65dsi86.c | 32 +++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index d55d19759796..0fc9e97b2d98 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -313,8 +313,7 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge)
goto err_dsi_host;
}
- /* TODO: setting to 4 lanes always for now */
- pdata->dp_lanes = 4;
+ /* TODO: setting to 4 MIPI lanes always for now */
dsi->lanes = 4;
dsi->format = MIPI_DSI_FMT_RGB888;
dsi->mode_flags = MIPI_DSI_MODE_VIDEO;
@@ -511,12 +510,41 @@ static void ti_sn_bridge_set_video_timings(struct ti_sn_bridge *pdata)
usleep_range(10000, 10500); /* 10ms delay recommended by spec */
}
+static unsigned int ti_sn_get_max_lanes(struct ti_sn_bridge *pdata)
+{
+ u8 data;
+ int ret;
+
+ ret = drm_dp_dpcd_readb(&pdata->aux, DP_MAX_LANE_COUNT, &data);
+ if (ret != 1) {
+ DRM_DEV_ERROR(pdata->dev,
+ "Can't read lane count (%d); assuming 4\n", ret);
+ return 4;
+ }
+
+ return data & DP_LANE_COUNT_MASK;
+}
+
static void ti_sn_bridge_enable(struct drm_bridge *bridge)
{
struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
unsigned int val;
int ret;
+ /*
+ * Run with the maximum number of lanes that the DP sink supports.
+ *
+ * Depending use cases, we might want to revisit this later because:
+ * - It's plausible that someone may have run fewer lines to the
+ * sink than the sink actually supports, assuming that the lines
+ * will just be driven at a higher rate.
+ * - The DP spec seems to indicate that it's more important to minimize
+ * the number of lanes than the link rate.
+ *
+ * If we do revisit, it would be important to measure the power impact.
+ */
+ pdata->dp_lanes = ti_sn_get_max_lanes(pdata);
+
/* DSI_A lane config */
val = CHA_DSI_LANES(4 - pdata->dsi->lanes);
regmap_update_bits(pdata->regmap, SN_DSI_LANES_REG,
--
2.24.1.735.g03f4e72817-goog
next prev parent reply other threads:[~2019-12-18 22:36 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 22:35 [PATCH v3 0/9] drm/bridge: ti-sn65dsi86: Improve support for AUO B116XAK01 + other DP Douglas Anderson
2019-12-18 22:35 ` [PATCH v3 1/9] drm/bridge: ti-sn65dsi86: Split the setting of the dp and dsi rates Douglas Anderson
2020-02-03 23:31 ` Bjorn Andersson
2019-12-18 22:35 ` [PATCH v3 2/9] drm/bridge: ti-sn65dsi86: zero is never greater than an unsigned int Douglas Anderson
2020-02-03 23:32 ` Bjorn Andersson
2019-12-18 22:35 ` [PATCH v3 3/9] drm/bridge: ti-sn65dsi86: Don't use MIPI variables for DP link Douglas Anderson
2020-02-03 23:33 ` Bjorn Andersson
2019-12-18 22:35 ` [PATCH v3 4/9] drm/bridge: ti-sn65dsi86: Config number of DP lanes Mo' Betta Douglas Anderson
2020-02-03 23:34 ` Bjorn Andersson
2019-12-18 22:35 ` Douglas Anderson [this message]
2020-02-03 23:35 ` [PATCH v3 5/9] drm/bridge: ti-sn65dsi86: Read num lanes from the DP sink Bjorn Andersson
2019-12-18 22:35 ` [PATCH v3 6/9] drm/bridge: ti-sn65dsi86: Use 18-bit DP if we can Douglas Anderson
2020-02-03 23:37 ` Bjorn Andersson
2020-02-04 0:21 ` Doug Anderson
2020-02-12 23:04 ` Doug Anderson
2020-02-13 9:17 ` Neil Armstrong
[not found] ` <20200710011935.GA7056@gentoo.org>
2020-07-10 1:38 ` Doug Anderson
2020-07-10 2:14 ` Doug Anderson
2020-07-10 3:12 ` Steev Klimaszewski
2020-07-10 3:17 ` Steev Klimaszewski
2020-07-10 3:43 ` Steev Klimaszewski
2020-07-10 4:12 ` Doug Anderson
2020-07-10 6:15 ` Steev Klimaszewski
2020-07-10 14:16 ` Rob Clark
2020-07-10 14:47 ` Doug Anderson
2020-07-10 17:10 ` Steev Klimaszewski
2020-07-14 15:31 ` Doug Anderson
2020-09-02 14:37 ` Doug Anderson
2019-12-18 22:35 ` [PATCH v3 7/9] drm/bridge: ti-sn65dsi86: Group DP link training bits in a function Douglas Anderson
2020-02-03 23:39 ` Bjorn Andersson
2019-12-18 22:35 ` [PATCH v3 8/9] drm/bridge: ti-sn65dsi86: Train at faster rates if slower ones fail Douglas Anderson
2020-02-03 23:41 ` Bjorn Andersson
2019-12-18 22:35 ` [PATCH v3 9/9] drm/bridge: ti-sn65dsi86: Avoid invalid rates Douglas Anderson
2020-02-03 23:43 ` Bjorn Andersson
2020-01-06 22:47 ` [PATCH v3 0/9] drm/bridge: ti-sn65dsi86: Improve support for AUO B116XAK01 + other DP Doug Anderson
2020-02-03 23:45 ` Bjorn Andersson
2020-02-13 9:51 ` Neil Armstrong
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