drm/udl: Reading all edid blocks in DRM/UDL driver

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 <tutankhamen@chromium.org>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171013001350.172155-2-tutankhamen@chromium.org

diff --git a/drivers/gpu/drm/udl/udl_connector.c b/drivers/gpu/drm/udl/udl_connector.c
index b4d1464..c0bbd1c 100644 (file)
--- 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) {
                kfree(udl_connector->edid);
                udl_connector->edid = NULL;
        }
 
-       edid = (struct edid *)udl_get_edid(udl);
-       if (!edid || !memchr_inv(edid, 0, EDID_LENGTH))
-               return connector_status_disconnected;
 
-       udl_connector->edid = edid;
-
-       /*
-        * We only read the main block, but if the monitor reports extension
-        * blocks then the drm edid code expects them to be present, so patch
-        * the extension count to 0.
-        */
-       udl_connector->edid->checksum +=
-                       udl_connector->edid->extensions;
-       udl_connector->edid->extensions = 0;
+       if (!udl_get_edid(udl, &edid_buff, &edid_buff_size))
+               return connector_status_disconnected;
 
+       udl_connector->edid = (struct edid *)edid_buff;
+       
        return connector_status_connected;
 }