Re: [PATCH v2 02/10] drm/bochs: Use helpers for struct drm_edid

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Hi

Am 23.09.24 um 06:35 schrieb Dmitry Baryshkov:
On Mon, Sep 02, 2024 at 12:53:40PM GMT, Thomas Zimmermann wrote:
Implement a read function for struct drm_edid and read the EDID data
with drm_edit_read_custom(). Update the connector data accordingly.

The EDID data comes from the emulator itself and the connector stores
a copy in its EDID property. The drm_edid field in struct bochs_device
is therefore not required. Remove it.

If qemu provides no EDID data, install default display modes as before.

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
  drivers/gpu/drm/tiny/bochs.c | 48 +++++++++++++++++-------------------
  1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
index 47a45a14306c..197fc00b373f 100644
--- a/drivers/gpu/drm/tiny/bochs.c
+++ b/drivers/gpu/drm/tiny/bochs.c
@@ -85,7 +85,6 @@ struct bochs_device {
  	u16 yres_virtual;
  	u32 stride;
  	u32 bpp;
-	const struct drm_edid *drm_edid;
/* drm */
  	struct drm_device *dev;
@@ -172,12 +171,14 @@ static void bochs_hw_set_little_endian(struct bochs_device *bochs)
  #define bochs_hw_set_native_endian(_b) bochs_hw_set_little_endian(_b)
  #endif
-static int bochs_get_edid_block(void *data, u8 *buf,
-				unsigned int block, size_t len)
+static int bochs_get_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
  {
  	struct bochs_device *bochs = data;
  	size_t i, start = block * EDID_LENGTH;
+ if (!bochs->mmio)
+		return -1;
+
  	if (start + len > 0x400 /* vga register offset */)
  		return -1;
@@ -187,25 +188,20 @@ static int bochs_get_edid_block(void *data, u8 *buf,
  	return 0;
  }
-static int bochs_hw_load_edid(struct bochs_device *bochs)
+static const struct drm_edid *bochs_hw_read_edid(struct drm_connector *connector)
  {
+	struct drm_device *dev = connector->dev;
+	struct bochs_device *bochs = dev->dev_private;
  	u8 header[8];
- if (!bochs->mmio)
-		return -1;
-
  	/* check header to detect whenever edid support is enabled in qemu */
  	bochs_get_edid_block(bochs, header, 0, ARRAY_SIZE(header));
  	if (drm_edid_header_is_valid(header) != 8)
I understand that you probably don't want to change the behaviour of the
driver, but maybe it's better to check drm_edid_read_custom return
value? Bochs, amdgpu and radeon are the only drivers that call
drm_edid_header_is_valid().

The nearby comment indicates that EDID support might not be present in qemu. But drm_edid_read_custom() warns in this case, even though it's a legal state. Hence the test.

Best regards
Thomas


-		return -1;
+		return NULL;

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)





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