linux-kernel - [PATCH 3/3] drm/ssd130x: Change "solomon,page-offset" property default value

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Date:   Thu, 16 Nov 2023 19:07:39 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Sahaj Sarup <sahaj.sarup@...aro.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...il.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH 3/3] drm/ssd130x: Change "solomon,page-offset" property default value

This is used to specify the page start address offset of the display RAM.

The value is used as offset when setting the page start address with the
SSD130X_SET_PAGE_RANGE command, and the driver currently sets its value to
1 if the property is not present in the Device Tree.

But the datasheet mentions that the value on reset for the page start is a
0, so it makes more sense to also have 0 as the default value for the page
offset if the property is not present.

In fact, using a default value of 1 leads to the display not working when
the emulated fbdev is attached to the framebuffer console.

Reported-by: Sahaj Sarup <sahaj.sarup@...aro.org>
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
---

 drivers/gpu/drm/solomon/ssd130x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index bef293922b98..8944129a8e0b 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -1453,7 +1453,7 @@ static void ssd130x_parse_properties(struct ssd130x_device *ssd130x)
 		ssd130x->height = ssd130x->device_info->default_height;
 
 	if (device_property_read_u32(dev, "solomon,page-offset", &ssd130x->page_offset))
-		ssd130x->page_offset = 1;
+		ssd130x->page_offset = 0;
 
 	if (device_property_read_u32(dev, "solomon,col-offset", &ssd130x->col_offset))
 		ssd130x->col_offset = 0;
-- 
2.41.0