Re: [PATCH 2/2] thunderbolt: Flush the ring interrupt status clear

[sashiko-bot@kernel.org]

> On hosts without QUIRK_AUTO_CLEAR_INT, ring_msix() clears the ring's
> bit in REG_RING_INT_CLEAR before it schedules ring_work(). This is a
> posted write and nothing is read from the NHI afterwards, so the clear
> can take effect after the next frame on the ring has completed. It
> then clears the status of that frame as well. The descriptor stays
> completed and the interrupt stays enabled, but no MSI-X is raised, and
> the frame waits until another interrupt on the ring runs ring_work().
> 
> Before commit 468c49f44759 ("thunderbolt: Disable interrupt auto clear
> for rings") the status was cleared by reading REG_RING_NOTIFY_BASE,
> and a read is not posted.
> 
> Read back REG_RING_INTERRUPT_BASE after the write, so the clear has
> taken effect before ring_work() looks at the descriptors. A frame that
> completed before that point is seen by ring_work(), and a later one
> [ ... ]
> 
> Fixes: 468c49f44759 ("thunderbolt: Disable interrupt auto clear for rings")
> Cc: stable@vger.kernel.org
> Cc: Mario Limonciello <superm1@kernel.org>
> Signed-off-by: Sven Neuhaus <sven-kernel@sven.de>

Sashiko has reviewed this patch and found no issues.

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