Re: [PATCH v2 2/2] drm/tyr: use IoMem directly instead of Devres

[Alice Ryhl <aliceryhl@google.com>]

On Fri, May 29, 2026 at 02:00:54AM +0200, Danilo Krummrich wrote:
> Now that IoMem is lifetime-parameterized, use it directly in probe
> rather than wrapping it in Devres and Arc. The I/O memory mapping is
> only used during probe and not stored in driver data, so device-managed
> revocation is unnecessary.
> 
> This removes the Devres access(dev) pattern from issue_soft_reset(),
> GpuInfo::new(), and l2_power_on(), simplifying register access.
> 
> Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>

> -pub(crate) type IoMem = kernel::io::mem::IoMem<'static, SZ_2M>;
> +pub(crate) type IoMem<'a> = kernel::io::mem::IoMem<'a, SZ_2M>;

It'd make more sense for me to put 'b or 'bound here.

>          let sram_regulator = Regulator::<regulator::Enabled>::get(pdev.as_ref(), c"sram")?;
>  
>          let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
> -        let iomem = Arc::new(request.iomap_sized::<SZ_2M>()?.into_devres()?, GFP_KERNEL)?;
> +        let iomem = request.iomap_sized::<SZ_2M>()?;
>  
>          issue_soft_reset(pdev.as_ref(), &iomem)?;
>          gpu::l2_power_on(pdev.as_ref(), &iomem)?;
>  
> -        let gpu_info = GpuInfo::new(pdev.as_ref(), &iomem)?;
> +        let gpu_info = GpuInfo::new(&iomem);


While this change is fine, I notice that we don't actually keep the
iomem alive past the probe method. I assume we're going to need that,
which leads to the question of whether we can store the iomem in the
places we need it.

As far as I can tell, we can store it in TyrPlatformDriverData but not
in TyrDrmDeviceData, is that right?

I guess it does make sense because the io memory goes away if the
underlying platform device (the bus) goes away, even if the drm device
still exists due to open fds from userspace.

Alice