On 5/18/22 20:48, Dexuan Cui wrote:
From: Dexuan Cui decui@microsoft.com Sent: Wednesday, May 4, 2022 10:05 AM To: Haiyang Zhang haiyangz@microsoft.com; Wei Liu wei.liu@kernel.org;
... When I initially implemented this driver 10 years ago, I believe there was smaller limit for the fb... But I think this patch is good for the newer MMIO alloc scheme. I hope to see reviews also from @Dexuan Cui @Michael Kelley (LINUX) who are more familiar with the PCI/BAR/MMIO area.
Thanks,
- Haiyang
The patch looks good to me but I suggest we check with the Hyper-V team to figure out how a Gen1 Windows VM supports a higher resolution that needs a VRAM size of more than 64MB. Just in case we miss something..
Thanks, -- Dexuan
Reviewed-by: Dexuan Cui decui@microsoft.com
Saurabh checked this with Hyper-V team, who said there is no Generation 1-specific block for larger VRAM sizes in Windows VM.
When the driver was originally developed, we didn't have the API vmbus_allocate_mmio(), and I guess we just used the PCI device's BAR address for simplicity, and didn't realize the restriction with very high resolutions that require >64 MB VRAM. It looks like the synthetic VMBus framebuffer device doesn't have to use the same MMIO range used by the Hyper-V legacy PCI framebuffer device, so the patch looks good to me.
Thanks for the review, Dexuan!
I've applied this patch now to the fbdev git tree.
BTW, please check the hyperv-drm driver as well: drivers/gpu/drm/hyperv/hyperv_drm_drv.c I think we should make the same change there to support 7680x4320 for Gen1 VMs.
Haiyang, can you check that as well and send another patch for the drm tree ?
Helge