From: "Anton V. Boyarshinov" <boyarsh@altlinux.org>

To calculate screen size in centimeters we should calculate:
pixels/dpi*2.54
but not
pixels*dpi/2540

Using wrong formula we actually get 65 DPI and very small fonts.

Signed-off-by: Anton V. Boyarshinov <boyarsh@altlinux.org>
Message-id: 20200226122054.366b9cda@table.localdomain
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/display/edid-generate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/display/edid-generate.c b/hw/display/edid-generate.c
index 75c945a94813..e58472fde501 100644
--- a/hw/display/edid-generate.c
+++ b/hw/display/edid-generate.c
@@ -360,8 +360,8 @@ void qemu_edid_generate(uint8_t *edid, size_t size,
     edid[20] = 0xa5;
 
     /* screen size: undefined */
-    edid[21] = info->prefx * info->dpi / 2540;
-    edid[22] = info->prefy * info->dpi / 2540;
+    edid[21] = info->prefx * 254 / 100 / info->dpi;
+    edid[22] = info->prefy * 254 / 100 / info->dpi;
 
     /* display gamma: 2.2 */
     edid[23] = 220 - 100;
-- 
2.18.2

Am 02.03.20 um 10:18 schrieb Gerd Hoffmann:

> From: "Anton V. Boyarshinov" <boyarsh@altlinux.org>
>
> To calculate screen size in centimeters we should calculate:
> pixels/dpi*2.54
> but not
> pixels*dpi/2540
>
> Using wrong formula we actually get 65 DPI and very small fonts.
>
> Signed-off-by: Anton V. Boyarshinov <boyarsh@altlinux.org>
> Message-id: 20200226122054.366b9cda@table.localdomain
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/display/edid-generate.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/display/edid-generate.c b/hw/display/edid-generate.c
> index 75c945a94813..e58472fde501 100644
> --- a/hw/display/edid-generate.c
> +++ b/hw/display/edid-generate.c
> @@ -360,8 +360,8 @@ void qemu_edid_generate(uint8_t *edid, size_t size,
>      edid[20] = 0xa5;
>  
>      /* screen size: undefined */
> -    edid[21] = info->prefx * info->dpi / 2540;
> -    edid[22] = info->prefy * info->dpi / 2540;
> +    edid[21] = info->prefx * 254 / 100 / info->dpi;
> +    edid[22] = info->prefy * 254 / 100 / info->dpi;


Gerd, the required rounding (see my previous e-mail) for both values is
still missing.

Cheers,

Stefan