[PATCH v5 2/3] winex11.drv: Add EDID to the virtual desktop monitor device.

[Zhiyi Zhang]

On 9/8/21 1:43 AM, Eduard Permyakov wrote:
> Some applications use the EDID property of the monitor device
> to detect supported resolutions, and set the viewport size. Add
> a computed EDID to the virtual desktop monitor device to allow
> the virtual desktop driver to be better compatible with such
> applications.
>
> Most fields of the EDID contain details that are of no relevance
> to applications, so populate only the native resolution and physical
> monitor dimensions. This should cover the vast majority of use
> cases.
>
> Signed-off-by: Eduard Permyakov <epermyakov at codeweavers.com>
> ---
>  dlls/winex11.drv/desktop.c | 75 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 73 insertions(+), 2 deletions(-)
>
> diff --git a/dlls/winex11.drv/desktop.c b/dlls/winex11.drv/desktop.c
> index 71b3a0a5a27..37e5624967e 100644
> --- a/dlls/winex11.drv/desktop.c
> +++ b/dlls/winex11.drv/desktop.c
> @@ -20,6 +20,7 @@
>   */
>  
>  #include "config.h"
> +#include <stdint.h>
>  #include <X11/cursorfont.h>
>  #include <X11/Xlib.h>
>  
> @@ -111,6 +112,74 @@ static void add_desktop_mode( DEVMODEW *mode, DWORD depth, DWORD width, DWORD he
>      mode->dmDisplayFrequency = 60;
>  }
>  
> +static void get_virtual_edid( unsigned char **edid, unsigned long *len )
> +{
> +    static const size_t desc_size = 128;

You can remove desc_size entirely and use sizeof(default_edid) instead.

> +    int i;
> +    uint8_t accum = 0;
> +    /*Sample EDID for an LCD Desktop IT Display, from VESA spec */
> +    static const unsigned char default_edid[128] = {
> +        /* Header */
> +        0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
> +        /* Manufacturer's code name */
> +        0x04, 0x43,
> +        /* Product code */
> +        0x06, 0xf2,
> +        /* Serial Number */
> +        0x01, 0x00, 0x00, 0x00,
> +        /* Date of manufacture */
> +        0x01, 0x11,
> +        /* EDID version */
> +        0x01, 0x04,
> +        /* Standard characteristics */
> +        0x0f, 0x2b, 0x20, 0x78, 0x2b, 0x9c, 0x68, 0xa0,
> +        0x57, 0x4a, 0x9b, 0x26, 0x12, 0x48, 0x4c, 0xff,
> +        0xff, 0x80, 0xa9, 0x59, 0xa9, 0x4f, 0xa9, 0x4a,
> +        0xa9, 0x45, 0x81, 0x99, 0x81, 0x80, 0x61, 0x59,
> +        0x45, 0x59,
> +        /* First 18-byte data block (Preferred Timing Mode) */
> +        0x48, 0x3f, 0x40, 0x30, 0x62, 0xb0, 0x32, 0x40,
> +        0x40, 0xc0, 0x13, 0x00, 0xab, 0x40, 0x11, 0x00,
> +        0x00, 0x1e,
> +        /* Second 18-byte data block */
> +        0x00, 0x00, 0x00, 0xfd, 0x00, 0x32, 0x5a, 0x1e,
> +        0x6e, 0x17, 0x04, 0x11, 0x00, 0xc8, 0x90, 0x00,
> +        0x50, 0x3c,
> +        /* Third 18-byte data block */
> +        0x00, 0x00, 0x00, 0xf7, 0x00, 0x0a, 0xf7, 0x0f,
> +        0x03, 0x87, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00,
> +        0x00, 0x00,
> +        /* Fourth 18-byte data block */
> +        0x00, 0x00, 0x00, 0xfc, 0x00, 0x41, 0x42, 0x43,
> +        0x20, 0x4c, 0x43, 0x44, 0x32, 0x31, 0x0a, 0x20,
> +        0x20, 0x20,
> +        /* Extension flag */
> +        0x00,
> +    };
> +
> +    *edid = heap_calloc( desc_size, 1 );
> +    if (!*edid)
> +    {
> +        *len = 0;
> +        return;
> +    }
> +
> +    memcpy( *edid, default_edid, sizeof(default_edid) );

You can use sizeof(default_edid) - 1 since you don't need to copy the last byte.

Anyway, I am not feeling comfortable with the current approach for generating fake EDID data.
It's not real enough. For example, physical size should reflect the recommended DPI values and
the resolution list should match what's reported from EnumDisplaySettings().

In my opinion, you can either generate an EDID by carefully following the VESA EDID standard,
or, the other way, which I think it's easier, is to pass the host primary monitor EDID to the
virtual desktop by introducing a get_host_primary_monitor_edid(), similar to what get_host_primary_gpu()
has done. This way has the benefit of not bothering with the EDID generation and has the
same EDID as the host, which can reduce the difference between using virtual desktop and
XRandR display device handlers. As for Xinerama, you can leave the EDID empty because
Xinerama is rarely used nowadays.

> +    *len = desc_size;
> +
> +    /* Set the native resolution in the Preferred Timing Mode descriptor */
> +    (*edid)[0x38] = max_width & 0xff;
> +    (*edid)[0x3a] = ((max_width >> 8) & 0xf) << 4;
> +
> +    (*edid)[0x3b] = max_height & 0xff;
> +    (*edid)[0x3d] = ((max_height >> 8) & 0xf) << 4;
> +
> +    /* Set checksum */
> +    for (i = 0; i < desc_size-1; i++)
> +        accum += (*edid)[i];
> +    (*edid)[desc_size - 1] = 256 - accum;
> +}
> +
>  static BOOL X11DRV_desktop_get_modes( ULONG_PTR id, DWORD flags, DEVMODEW **new_modes, UINT *mode_count )
>  {
>      UINT depth_idx, size_idx, mode_idx = 0;
> @@ -265,8 +334,7 @@ static BOOL X11DRV_desktop_get_monitors( ULONG_PTR adapter_id, struct x11drv_mon
>      SetRect( &monitor->rc_work, 0, 0, desktop_width, desktop_height );
>      query_desktop_work_area( &monitor->rc_work );
>      monitor->state_flags = DISPLAY_DEVICE_ATTACHED;
> -    monitor->edid_len = 0;
> -    monitor->edid = NULL;
> +    get_virtual_edid( &monitor->edid, &monitor->edid_len );
>      if (desktop_width && desktop_height)
>          monitor->state_flags |= DISPLAY_DEVICE_ACTIVE;
>  
> @@ -277,6 +345,9 @@ static BOOL X11DRV_desktop_get_monitors( ULONG_PTR adapter_id, struct x11drv_mon
>  
>  static void X11DRV_desktop_free_monitors( struct x11drv_monitor *monitors, int count )
>  {
> +    int i;
> +    for (i = 0; i < count; i++)
> +        heap_free( monitors[i].edid );
>      heap_free( monitors );
>  }
>