Re: [PATCH 2/2] drm/udl: Reading all edid blocks in DRM/UDL driver

[Alex Deucher]

On Thu, Oct 12, 2017 at 8:13 PM, Robert Tarasov
 wrote:
> Now DRM/UDL driver retreives all edid data blocks instead of only base one.
> Previous approch could lead to improper initialization of video mode with
> certain monitors.
>
> Signed-off-by: Robert Tarasov 

Reviewed-by: Alex Deucher 

> ---
>  drivers/gpu/drm/udl/udl_connector.c | 106 
> +++-
>  1 file changed, 68 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_connector.c 
> b/drivers/gpu/drm/udl/udl_connector.c
> index 6a9250ac8f29..c3dc1fd20cb4 100644
> --- a/drivers/gpu/drm/udl/udl_connector.c
> +++ b/drivers/gpu/drm/udl/udl_connector.c
> @@ -17,42 +17,79 @@
>  #include "udl_connector.h"
>  #include "udl_drv.h"
>
> -/* dummy connector to just get EDID,
> -   all UDL appear to have a DVI-D */
> -
> -static u8 *udl_get_edid(struct udl_device *udl)
> +static bool udl_get_edid_block(struct udl_device *udl, int block_idx,
> +  u8 *buff)
>  {
> -   u8 *block;
> -   char *rbuf;
> int ret, i;
> +   u8 *read_buff;
>
> -   block = kmalloc(EDID_LENGTH, GFP_KERNEL);
> -   if (block == NULL)
> -   return NULL;
> -
> -   rbuf = kmalloc(2, GFP_KERNEL);
> -   if (rbuf == NULL)
> -   goto error;
> +   read_buff = kmalloc(2, GFP_KERNEL);
> +   if (!read_buff)
> +   return false;
>
> for (i = 0; i < EDID_LENGTH; i++) {
> +   int bval = (i + block_idx * EDID_LENGTH) << 8;
> ret = usb_control_msg(udl->udev,
> - usb_rcvctrlpipe(udl->udev, 0), (0x02),
> - (0x80 | (0x02 << 5)), i << 8, 0xA1, 
> rbuf, 2,
> - HZ);
> + usb_rcvctrlpipe(udl->udev, 0),
> + (0x02), (0x80 | (0x02 << 5)), bval,
> + 0xA1, read_buff, 2, HZ);
> if (ret < 1) {
> DRM_ERROR("Read EDID byte %d failed err %x\n", i, 
> ret);
> -   goto error;
> +   kfree(read_buff);
> +   return false;
> }
> -   block[i] = rbuf[1];
> +   buff[i] = read_buff[1];
> }
>
> -   kfree(rbuf);
> -   return block;
> +   kfree(read_buff);
> +   return true;
> +}
>
> -error:
> -   kfree(block);
> -   kfree(rbuf);
> -   return NULL;
> +static bool udl_get_edid(struct udl_device *udl, u8 **result_buff,
> +int *result_buff_size)
> +{
> +   int i, extensions;
> +   u8 *block_buff = NULL, *buff_ptr;
> +
> +   block_buff = kmalloc(EDID_LENGTH, GFP_KERNEL);
> +   if (block_buff == NULL)
> +   return false;
> +
> +   if (udl_get_edid_block(udl, 0, block_buff) &&
> +   memchr_inv(block_buff, 0, EDID_LENGTH)) {
> +   extensions = ((struct edid *)block_buff)->extensions;
> +   if (extensions > 0) {
> +   /* we have to read all extensions one by one */
> +   *result_buff_size = EDID_LENGTH * (extensions + 1);
> +   *result_buff = kmalloc(*result_buff_size, GFP_KERNEL);
> +   buff_ptr = *result_buff;
> +   if (buff_ptr == NULL) {
> +   kfree(block_buff);
> +   return false;
> +   }
> +   memcpy(buff_ptr, block_buff, EDID_LENGTH);
> +   kfree(block_buff);
> +   buff_ptr += EDID_LENGTH;
> +   for (i = 1; i < extensions; ++i) {
> +   if (udl_get_edid_block(udl, i, buff_ptr)) {
> +   buff_ptr += EDID_LENGTH;
> +   } else {
> +   kfree(*result_buff);
> +   *result_buff = NULL;
> +   return false;
> +   }
> +   }
> +   return true;
> +   }
> +   /* we have only base edid block */
> +   *result_buff = block_buff;
> +   *result_buff_size = EDID_LENGTH;
> +   return true;
> +   }
> +
> +   kfree(block_buff);
> +
> +   return false;
>  }
>
>  static int udl_get_modes(struct drm_connector *connector)
> @@ -84,33 +121,26 @@ static int udl_mode_valid(struct drm_connector 
> *connector,
>  static enum drm_connector_status
>  udl_detect(struct drm_connector *connector, bool force)
>  {
> -   struct edid *edid;
> +   u8 *edid_buff = NULL;
> +   int edid_buff_size = 0;
> 

[PATCH 2/2] drm/udl: Reading all edid blocks in DRM/UDL driver

[Robert Tarasov]

Now DRM/UDL driver retreives all edid data blocks instead of only base one.
Previous approch could lead to improper initialization of video mode with
certain monitors.

Signed-off-by: Robert Tarasov 
---
 drivers/gpu/drm/udl/udl_connector.c | 106 +++-
 1 file changed, 68 insertions(+), 38 deletions(-)

diff --git a/drivers/gpu/drm/udl/udl_connector.c 
b/drivers/gpu/drm/udl/udl_connector.c
index 6a9250ac8f29..c3dc1fd20cb4 100644
--- a/drivers/gpu/drm/udl/udl_connector.c
+++ b/drivers/gpu/drm/udl/udl_connector.c
@@ -17,42 +17,79 @@
 #include "udl_connector.h"
 #include "udl_drv.h"
 
-/* dummy connector to just get EDID,
-   all UDL appear to have a DVI-D */
-
-static u8 *udl_get_edid(struct udl_device *udl)
+static bool udl_get_edid_block(struct udl_device *udl, int block_idx,
+  u8 *buff)
 {
-   u8 *block;
-   char *rbuf;
int ret, i;
+   u8 *read_buff;
 
-   block = kmalloc(EDID_LENGTH, GFP_KERNEL);
-   if (block == NULL)
-   return NULL;
-
-   rbuf = kmalloc(2, GFP_KERNEL);
-   if (rbuf == NULL)
-   goto error;
+   read_buff = kmalloc(2, GFP_KERNEL);
+   if (!read_buff)
+   return false;
 
for (i = 0; i < EDID_LENGTH; i++) {
+   int bval = (i + block_idx * EDID_LENGTH) << 8;
ret = usb_control_msg(udl->udev,
- usb_rcvctrlpipe(udl->udev, 0), (0x02),
- (0x80 | (0x02 << 5)), i << 8, 0xA1, rbuf, 
2,
- HZ);
+ usb_rcvctrlpipe(udl->udev, 0),
+ (0x02), (0x80 | (0x02 << 5)), bval,
+ 0xA1, read_buff, 2, HZ);
if (ret < 1) {
DRM_ERROR("Read EDID byte %d failed err %x\n", i, ret);
-   goto error;
+   kfree(read_buff);
+   return false;
}
-   block[i] = rbuf[1];
+   buff[i] = read_buff[1];
}
 
-   kfree(rbuf);
-   return block;
+   kfree(read_buff);
+   return true;
+}
 
-error:
-   kfree(block);
-   kfree(rbuf);
-   return NULL;
+static bool udl_get_edid(struct udl_device *udl, u8 **result_buff,
+int *result_buff_size)
+{
+   int i, extensions;
+   u8 *block_buff = NULL, *buff_ptr;
+
+   block_buff = kmalloc(EDID_LENGTH, GFP_KERNEL);
+   if (block_buff == NULL)
+   return false;
+
+   if (udl_get_edid_block(udl, 0, block_buff) &&
+   memchr_inv(block_buff, 0, EDID_LENGTH)) {
+   extensions = ((struct edid *)block_buff)->extensions;
+   if (extensions > 0) {
+   /* we have to read all extensions one by one */
+   *result_buff_size = EDID_LENGTH * (extensions + 1);
+   *result_buff = kmalloc(*result_buff_size, GFP_KERNEL);
+   buff_ptr = *result_buff;
+   if (buff_ptr == NULL) {
+   kfree(block_buff);
+   return false;
+   }
+   memcpy(buff_ptr, block_buff, EDID_LENGTH);
+   kfree(block_buff);
+   buff_ptr += EDID_LENGTH;
+   for (i = 1; i < extensions; ++i) {
+   if (udl_get_edid_block(udl, i, buff_ptr)) {
+   buff_ptr += EDID_LENGTH;
+   } else {
+   kfree(*result_buff);
+   *result_buff = NULL;
+   return false;
+   }
+   }
+   return true;
+   }
+   /* we have only base edid block */
+   *result_buff = block_buff;
+   *result_buff_size = EDID_LENGTH;
+   return true;
+   }
+
+   kfree(block_buff);
+
+   return false;
 }
 
 static int udl_get_modes(struct drm_connector *connector)
@@ -84,33 +121,26 @@ static int udl_mode_valid(struct drm_connector *connector,
 static enum drm_connector_status
 udl_detect(struct drm_connector *connector, bool force)
 {
-   struct edid *edid;
+   u8 *edid_buff = NULL;
+   int edid_buff_size = 0;
struct udl_device *udl = connector->dev->dev_private;
struct udl_drm_connector *udl_connector =
container_of(connector,
struct udl_drm_connector,
connector);
 
+   /* cleanup previous edid */
if (udl_connector->edid != NULL) {