linux-kernel - Re: [PATCH 2/2] thunderbolt: Disable interrupt auto clear for rings

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Date:   Mon, 13 Mar 2023 07:46:54 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        Basavaraj Natikar <Basavaraj.Natikar@....com>,
        Sanjay R Mehta <sanju.mehta@....com>, anson.tsao@....com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] thunderbolt: Disable interrupt auto clear for rings

Hi Mario,

On Fri, Mar 10, 2023 at 11:20:50AM -0600, Mario Limonciello wrote:
> When interrupt auto clear is programmed, any read to the interrupt
> status register will clear all interrupts.  If two interrupts have
> come in before one can be serviced then this will cause lost interrupts.
> 
> On AMD USB4 routers this has manifested in odd problems particularly
> with long strings of control tranfers such as reading the DROM via bit
> banging.

Nice catch! Does this mean we can drop [1] now?

[1] https://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt.git/commit/?h=next&id=8d7f459107f74fbbdde3dd5b3874d2e748cb8a21

I would still like to keep the nice refactor you did for the DROM
parsing, though.