Re: [PATCH v2] pci: quirks: Disable native PCIe hotplug on MSI Claw A8 root bridge

[Lukas Wunner <lukas@wunner.de>]

On Mon, Aug 10, 2026 at 01:57:58PM -0700, Derek John Clark wrote:
> I was able to drill down further. When the mmc device gets to
> blk_report_disk_dead() in block/genhd.c there is an xa_for_each loop.
> On the second loop of that it seems to hang in bdev_mark_dead(). That
> sets a callback that runs fs_bdev_mark_dead() which then runs
> sync_filesystem(). This is all hit because the "surprise" bool is set
> to false unconditionally in __del_gendisk().
> 
> Commenting out this from __del_gendisk():
> if (!test_bit(GD_DEAD, &disk->state))
>  blk_report_disk_dead(disk, false);
> 
> Avoids the hang.

Thank you so much, you've root-caused the issue:  We're missing a call
to blk_mark_disk_dead() at the top of rtsx_pci_sdmmc_drv_remove()
if the underlying pci_dev is marked disconnected.  Let me get back
to you with a fix in a bit.

> I'm not sure how much further we want to go down into this as we've
> moved quite far out of the driver space and are now well into the
> block subsystem. I'm working on a proof of concept that would allow
> the driver to inform the mmc core that this was a surprise, but I'm
> not sure how that would land. From what I've read the mmc core was
> intentionally detached from higher level drivers, though a few
> notification methods do exist. If I get that fully working I'll post
> it here but it will probably be a few days as I've run into some other
> obligations this week.

It's fine, you don't need to invest any more time into that and
I understand your frustration about how much effort is necessary
to fix this.

The issue you've found affects anyone removing e.g. a Thunderbolt-
attached dock with an MMC card reader during system sleep.  So it's
useful and important to have root-caused and fix that.  Unfortunately
kernel development often means getting sidetracked like this.

> I suppose that is true, but in that case we still wouldn't be able to
> use it as the root fs since it gets removed/re-added during a suspend.
> Would the quirk I submitted not have this compromise?

Okay I wasn't sure that using the MMC card as root filesystem
is even possible on this product.  If that's a potential use case,
it needs a separate fix.  I'll come up with a proposal for that one
as well.

Thanks,

Lukas