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Message-ID: <20190826220807.GK5031@pendragon.ideasonboard.com>
Date: Tue, 27 Aug 2019 01:08:07 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Andrey Smirnov <andrew.smirnov@...il.com>
Cc: dri-devel@...ts.freedesktop.org,
Andrzej Hajda <a.hajda@...sung.com>,
Tomi Valkeinen <tomi.valkeinen@...com>,
Cory Tusar <cory.tusar@....aero>,
Chris Healy <cphealy@...il.com>,
Lucas Stach <l.stach@...gutronix.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: tc358767: Expose test mode functionality via
debugfs
Hi Andrey,
Thank you for the patch.
On Mon, Aug 26, 2019 at 11:25:24AM -0700, Andrey Smirnov wrote:
> Presently, the driver code artificially limits test pattern mode to a
> single pattern with fixed color selection. It being a kernel module
> parameter makes switching "test patter" <-> "proper output" modes
> on-the-fly clunky and outright impossible if the driver is built into
> the kernel.
>
> To improve the situation a bit, convert current test pattern code to
> use debugfs instead by exposing "TestCtl" register. This way old
> "tc_test_pattern=1" functionality can be emulated via:
>
> echo -n 0x78146312 > tstctl
>
> and switch back to regular mode can be done with:
>
> echo -n 0x78146310 > tstctl
Can't we make this more userfriendly by exposing either a test pattern
index, or a string ? Do all bits in the register need to be controlled
from userspace ?
> Note that switching to any of the test patterns, will NOT trigger link
> re-establishment whereas switching to normal operation WILL. This is
> done so:
>
> a) we can isolate and verify (e)DP link functionality by switching to
> one of the test patters
>
> b) trigger a link re-establishment by switching back to normal mode
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
> Cc: Andrzej Hajda <a.hajda@...sung.com>
> Cc: Laurent Pinchart <Laurent.pinchart@...asonboard.com>
> Cc: Tomi Valkeinen <tomi.valkeinen@...com>
> Cc: Cory Tusar <cory.tusar@....aero>
> Cc: Chris Healy <cphealy@...il.com>
> Cc: Lucas Stach <l.stach@...gutronix.de>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-kernel@...r.kernel.org
> ---
> drivers/gpu/drm/bridge/tc358767.c | 137 ++++++++++++++++++++++--------
> 1 file changed, 101 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
> index 6308d93ad91d..7a795b613ed0 100644
> --- a/drivers/gpu/drm/bridge/tc358767.c
> +++ b/drivers/gpu/drm/bridge/tc358767.c
> @@ -17,6 +17,7 @@
>
> #include <linux/bitfield.h>
> #include <linux/clk.h>
> +#include <linux/debugfs.h>
> #include <linux/device.h>
> #include <linux/gpio/consumer.h>
> #include <linux/i2c.h>
> @@ -222,11 +223,10 @@
> #define COLOR_B GENMASK(15, 8)
> #define ENI2CFILTER BIT(4)
> #define COLOR_BAR_MODE GENMASK(1, 0)
> +#define COLOR_BAR_MODE_NORMAL 0
> #define COLOR_BAR_MODE_BARS 2
> -#define PLL_DBG 0x0a04
>
> -static bool tc_test_pattern;
> -module_param_named(test, tc_test_pattern, bool, 0644);
I assume that his being a debug feature there's no system relying on the
module parameter that would break if you remove it ?
> +#define PLL_DBG 0x0a04
>
> struct tc_edp_link {
> struct drm_dp_link base;
> @@ -789,16 +789,6 @@ static int tc_set_video_mode(struct tc_data *tc,
> if (ret)
> return ret;
>
> - /* Test pattern settings */
> - ret = regmap_write(tc->regmap, TSTCTL,
> - FIELD_PREP(COLOR_R, 120) |
> - FIELD_PREP(COLOR_G, 20) |
> - FIELD_PREP(COLOR_B, 99) |
> - ENI2CFILTER |
> - FIELD_PREP(COLOR_BAR_MODE, COLOR_BAR_MODE_BARS));
> - if (ret)
> - return ret;
> -
> /* DP Main Stream Attributes */
> vid_sync_dly = hsync_len + left_margin + mode->hdisplay;
> ret = regmap_write(tc->regmap, DP0_VIDSYNCDELAY,
> @@ -1150,14 +1140,6 @@ static int tc_stream_enable(struct tc_data *tc)
>
> dev_dbg(tc->dev, "enable video stream\n");
>
> - /* PXL PLL setup */
> - if (tc_test_pattern) {
> - ret = tc_pxl_pll_en(tc, clk_get_rate(tc->refclk),
> - 1000 * tc->mode.clock);
> - if (ret)
> - return ret;
> - }
> -
> ret = tc_set_video_mode(tc, &tc->mode);
> if (ret)
> return ret;
> @@ -1186,12 +1168,8 @@ static int tc_stream_enable(struct tc_data *tc)
> if (ret)
> return ret;
> /* Set input interface */
> - value = DP0_AUDSRC_NO_INPUT;
> - if (tc_test_pattern)
> - value |= DP0_VIDSRC_COLOR_BAR;
> - else
> - value |= DP0_VIDSRC_DPI_RX;
> - ret = regmap_write(tc->regmap, SYSCTRL, value);
> + ret = regmap_write(tc->regmap, SYSCTRL,
> + DP0_AUDSRC_NO_INPUT | DP0_VIDSRC_DPI_RX);
> if (ret)
> return ret;
>
> @@ -1220,39 +1198,44 @@ static void tc_bridge_pre_enable(struct drm_bridge *bridge)
> drm_panel_prepare(tc->panel);
> }
>
> -static void tc_bridge_enable(struct drm_bridge *bridge)
> +static int __tc_bridge_enable(struct tc_data *tc)
> {
> - struct tc_data *tc = bridge_to_tc(bridge);
> int ret;
>
> ret = tc_get_display_props(tc);
> if (ret < 0) {
> dev_err(tc->dev, "failed to read display props: %d\n", ret);
> - return;
> + return ret;
> }
>
> ret = tc_main_link_enable(tc);
> if (ret < 0) {
> dev_err(tc->dev, "main link enable error: %d\n", ret);
> - return;
> + return ret;
> }
>
> ret = tc_stream_enable(tc);
> if (ret < 0) {
> dev_err(tc->dev, "main link stream start error: %d\n", ret);
> tc_main_link_disable(tc);
> - return;
> }
>
> - drm_panel_enable(tc->panel);
> + return ret;
> }
>
> -static void tc_bridge_disable(struct drm_bridge *bridge)
> +static void tc_bridge_enable(struct drm_bridge *bridge)
> {
> struct tc_data *tc = bridge_to_tc(bridge);
> - int ret;
>
> - drm_panel_disable(tc->panel);
> + if (__tc_bridge_enable(tc) < 0)
> + return;
> +
> + drm_panel_enable(tc->panel);
> +}
> +
> +static int __tc_bridge_disable(struct tc_data *tc)
> +{
> + int ret;
>
> ret = tc_stream_disable(tc);
> if (ret < 0)
> @@ -1261,6 +1244,16 @@ static void tc_bridge_disable(struct drm_bridge *bridge)
> ret = tc_main_link_disable(tc);
> if (ret < 0)
> dev_err(tc->dev, "main link disable error: %d\n", ret);
> +
> + return ret;
> +}
> +
> +static void tc_bridge_disable(struct drm_bridge *bridge)
> +{
> + struct tc_data *tc = bridge_to_tc(bridge);
> +
> + drm_panel_disable(tc->panel);
> + __tc_bridge_disable(tc);
> }
>
> static void tc_bridge_post_disable(struct drm_bridge *bridge)
> @@ -1372,6 +1365,77 @@ static enum drm_connector_status tc_connector_detect(struct drm_connector *conne
> return connector_status_disconnected;
> }
>
> +static int tc_tstctl_set(void *data, u64 val)
> +{
> + struct tc_data *tc = data;
> + int ret;
> +
> + if (FIELD_GET(COLOR_BAR_MODE, val) == COLOR_BAR_MODE_NORMAL) {
> + ret = regmap_write(tc->regmap, SYSCTRL, DP0_VIDSRC_DPI_RX);
> + if (ret) {
> + dev_err(tc->dev,
> + "failed to select dpi video stream\n");
> + return ret;
> + }
> +
> + ret = regmap_write(tc->regmap, TSTCTL, val | ENI2CFILTER);
> + if (ret) {
> + dev_err(tc->dev, "failed to set TSTCTL\n");
> + return ret;
> + }
> +
> + ret = tc_pxl_pll_dis(tc);
> + if (ret) {
> + dev_err(tc->dev, "failed to disable PLL\n");
> + return ret;
> + }
> +
> + /*
> + * Re-establish DP link
> + */
> + ret = __tc_bridge_disable(tc);
> + if (ret)
> + return ret;
> +
> + ret = __tc_bridge_enable(tc);
> + if (ret)
> + return ret;
If the bridge is currently disabled you should not enable it. I think
you need to guard against race conditions with the enable/disable
functions, as well as delay writes until the bridge gets enabled if it
is currently disabled.
> + } else {
> + ret = tc_pxl_pll_en(tc, clk_get_rate(tc->refclk),
> + 1000 * tc->mode.clock);
> + if (ret) {
> + dev_err(tc->dev, "failed to enable PLL\n");
> + return ret;
> + }
> +
> + ret = regmap_write(tc->regmap, TSTCTL, val | ENI2CFILTER);
> + if (ret) {
> + dev_err(tc->dev, "failed to set TSTCTL\n");
> + return ret;
> + }
> +
> + ret = regmap_write(tc->regmap, SYSCTRL, DP0_VIDSRC_COLOR_BAR);
> + if (ret) {
> + dev_err(tc->dev, "failed to color bar video stream\n");
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(tc_tstctl_fops, NULL, tc_tstctl_set, "%llu\n");
Shouldn't you also provide a get handler ?
> +static int tc_late_register(struct drm_connector *connector)
> +{
> + if (connector->debugfs_entry)
> + debugfs_create_file_unsafe("tstctl", 0644,
> + connector->debugfs_entry,
> + connector_to_tc(connector),
> + &tc_tstctl_fops);
> + return 0;
> +}
Why a .late_register() handler, can't you do this at probe time ?
> static const struct drm_connector_funcs tc_connector_funcs = {
> .detect = tc_connector_detect,
> .fill_modes = drm_helper_probe_single_connector_modes,
> @@ -1379,6 +1443,7 @@ static const struct drm_connector_funcs tc_connector_funcs = {
> .reset = drm_atomic_helper_connector_reset,
> .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> + .late_register = tc_late_register,
> };
>
> static int tc_bridge_attach(struct drm_bridge *bridge)
--
Regards,
Laurent Pinchart
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