linux-kernel - [PATCH 1/3] drm/panel-edp: Add panel entry for R140NWF5 RH

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Date:   Tue, 19 Jul 2022 16:38:54 -0400
From:   Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, kernel@...labora.com,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>, Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Sam Ravnborg <sam@...nborg.org>,
        Thierry Reding <thierry.reding@...il.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] drm/panel-edp: Add panel entry for R140NWF5 RH

Add panel identification entry for the IVO R140NWF5 RH (product ID:
0x057d) panel.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>

---
The comments on the driver indicate that the T3 timing should be set on
hpd_absent, while hpd_reliable would have a shorter time just while the
HPD line stabilizes on low after power is supplied.

But can we really assume that the HPD line will be reliable at all
before the DDIC is done booting up, at which point the HPD line is
brought up? IOW, shouldn't we always delay T3 (by setting hpd_reliable =
T3), since only then we're really sure that the DDIC is done setting up
and the HPD line is reliable?

I've set the T3 delay to hpd_absent in this series, following what's
instructed in the comments, but I'd like to discuss whether we shouldn't
be setting T3 on hpd_reliable instead, for all panels, to be on the
safer side.

 drivers/gpu/drm/panel/panel-edp.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
index 3626469c4cc2..675d793d925e 100644
--- a/drivers/gpu/drm/panel/panel-edp.c
+++ b/drivers/gpu/drm/panel/panel-edp.c
@@ -1854,6 +1854,12 @@ static const struct panel_delay delay_100_500_e200 = {
 	.enable = 200,
 };
 
+static const struct panel_delay delay_200_500_e200 = {
+	.hpd_absent = 200,
+	.unprepare = 500,
+	.enable = 200,
+};
+
 #define EDP_PANEL_ENTRY(vend_chr_0, vend_chr_1, vend_chr_2, product_id, _delay, _name) \
 { \
 	.name = _name, \
@@ -1882,6 +1888,8 @@ static const struct edp_panel_entry edp_panels[] = {
 
 	EDP_PANEL_ENTRY('C', 'M', 'N', 0x114c, &innolux_n116bca_ea1.delay, "N116BCA-EA1"),
 
+	EDP_PANEL_ENTRY('I', 'V', 'O', 0x057d, &delay_200_500_e200, "R140NWF5 RH"),
+
 	EDP_PANEL_ENTRY('K', 'D', 'B', 0x0624, &kingdisplay_kd116n21_30nv_a010.delay, "116N21-30NV-A010"),
 	EDP_PANEL_ENTRY('K', 'D', 'B', 0x1120, &delay_200_500_e80_d50, "116N29-30NK-C007"),
 
-- 
2.37.0