Re: [PATCH] drm/xe/mmio: Assert MMIO is available

[Raag Jadav <raag.jadav@intel.com>]

On Thu, May 28, 2026 at 07:34:58PM +0200, Michal Wajdeczko wrote:
> On 5/28/2026 6:47 PM, Matthew Auld wrote:
> > On 28/05/2026 17:16, Michal Wajdeczko wrote:

...

> >> and the fact that mmio.regs is still non-NULL and points to the connected HW, is just our luck?
> >>
> >> maybe we should kill the HW immediately on pci.remove, if it is still present, and just unwind SW state using devm/drmm actions?
> > 
> > devm is for unwinding hw related state, 
> 
> hmm, are we 100% sure?
> 
> from [1] it looks that the devres rationale was about "leaking resources" problem and the example still shows that HW cleanup is part of the .remove hook:
> 
> my_remove_one()
> {
>       unregister_from_upper_layer(d);
>       shutdown_my_hardware();
> }
> 
> so maybe indeed we are little abusing the device model by touching the HW beyond the .remove?
> 
> [1] https://docs.kernel.org/driver-api/driver-model/devres.html

I'm doubtful because PCI core also hooks its hardware cleanup to devres.

1. pcim_enable_device()
2. pcim_set_mwi()
3. pcim_setup_msi_release()

Raag