[PATCH v2 1/3] efi: try to use the currently set GOP mode

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Modify efi_find_gop_mode() so that passing cols or rows as 0 is
interpreted as a request to attempt to keep the currently set mode,
and do so if the mode query for information is successful and the depth
is supported.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Changes since v1:
 - Only update cols or rows if the value is 0.
 - Leave depth alone.
---
 xen/common/efi/boot.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index b69c83e354..766a2553be 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -930,6 +930,27 @@ static UINTN __init 
efi_find_gop_mode(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop,
     UINTN gop_mode = ~0, info_size, size;
     unsigned int i;
 
+    if ( (!cols || !rows) && gop->Mode->Mode < gop->Mode->MaxMode )
+    {
+        /* If no (valid) resolution suggested, try to use the current mode. */
+        status = gop->QueryMode(gop, gop->Mode->Mode, &info_size, &mode_info);
+        if ( EFI_ERROR(status) )
+            PrintErr(L"Invalid current graphics mode\r\n");
+        else if ( mode_info->PixelFormat < PixelBltOnly )
+            return gop->Mode->Mode;
+        else
+        {
+            /*
+             * Try to find a mode with the same resolution and a valid pixel
+             * format.
+             */
+            if ( !cols )
+                cols = mode_info->HorizontalResolution;
+            if ( !rows )
+                rows = mode_info->VerticalResolution;
+        }
+    }
+
     for ( i = size = 0; i < gop->Mode->MaxMode; ++i )
     {
         unsigned int bpp = 0;
-- 
2.40.0