On Wed, 7 Sept 2022 at 11:15, Gerd Hoffmann <kra...@redhat.com> wrote:
>
> Add VgaInb() helper function to read vga registers. With that in place
> fix the unblanking. We need to put the ATT_ADDRESS_REGISTER flip flop
> into a known state, which is done by reading the
> INPUT_STATUS_1_REGISTER. Reading the INPUT_STATUS_1_REGISTER only works
> when the device is in color mode, so make sure that bit (0x01) is set in
> MISC_OUTPUT_REGISTER.
>
> Currently the mode setting works more by luck because
> ATT_ADDRESS_REGISTER flip flop happens to be in the state we need.
>
> Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
Merged as #3310
Thanks,
> ---
> OvmfPkg/QemuVideoDxe/Driver.c | 33 ++++++++++++++++++++++++++++++++-
> 1 file changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/OvmfPkg/QemuVideoDxe/Driver.c b/OvmfPkg/QemuVideoDxe/Driver.c
> index b91909a14e59..1f9ba046ef04 100644
> --- a/OvmfPkg/QemuVideoDxe/Driver.c
> +++ b/OvmfPkg/QemuVideoDxe/Driver.c
> @@ -984,6 +984,33 @@ VgaOutb (
> }
> }
>
> +UINT8
> +VgaInb (
> + QEMU_VIDEO_PRIVATE_DATA *Private,
> + UINTN Reg
> + )
> +{
> + EFI_STATUS Status;
> + UINT8 Data;
> +
> + if (Private->Variant == QEMU_VIDEO_BOCHS_MMIO) {
> + Data = 0;
> + Status = Private->PciIo->Mem.Read (
> + Private->PciIo,
> + EfiPciIoWidthUint8,
> + PCI_BAR_IDX2,
> + 0x400 - 0x3c0 + Reg,
> + 1,
> + &Data
> + );
> + ASSERT_EFI_ERROR (Status);
> + } else {
> + Data = inb (Private, Reg);
> + }
> +
> + return Data;
> +}
> +
> VOID
> InitializeBochsGraphicsMode (
> QEMU_VIDEO_PRIVATE_DATA *Private,
> @@ -998,7 +1025,11 @@ InitializeBochsGraphicsMode (
> ModeData->ColorDepth
> ));
>
> - /* unblank */
> + /* set color mode */
> + VgaOutb (Private, MISC_OUTPUT_REGISTER, 0x01);
> +
> + /* reset flip flop + unblank */
> + VgaInb (Private, INPUT_STATUS_1_REGISTER);
> VgaOutb (Private, ATT_ADDRESS_REGISTER, 0x20);
>
> BochsWrite (Private, VBE_DISPI_INDEX_ENABLE, 0);
> --
> 2.37.3
>
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