From: "Sudhakar Rajashekhara" <sudhakar.raj-l0cyMroinI0@public.gmane.org>
To: 'Jon Povey' <jon.povey-Ean/AyPsLtfkYMGBc/C6ZA@public.gmane.org>,
davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org
Cc: "'Jean Delvare (PC drivers,
core)'" <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>,
'Philby John' <pjohn-k0rHJ+Hhz/SB+jHODAdFcQ@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
"'Ben Dooks (embedded platforms)'"
<ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: RE: [PATCH] i2c: davinci: Fix race when setting up for TX
Date: Tue, 22 Jun 2010 17:47:59 +0530 [thread overview]
Message-ID: <41914.2560022466$1277209387@news.gmane.org> (raw)
In-Reply-To: <1277191864-5024-1-git-send-email-jon.povey-Ean/AyPsLtfkYMGBc/C6ZA@public.gmane.org>
Hi,
On Tue, Jun 22, 2010 at 13:01:03, Jon Povey wrote:
> Move the interrupt enable after the first byte load for TX, as it
> was racing with the interrupt handler and corrupting dev->buf_len
> for messages > 1 byte.
>
> Tested on DM355.
>
> Signed-off-by: Jon Povey <jon.povey-Ean/AyPsLtfkYMGBc/C6ZA@public.gmane.org>
> ---
> The race seems to have been introduced by 869e6692d527983958216f13c3c8e095791909df
>
> This fixes the problem for me, but someone from TI might want to comment
> on the validity of starting the transfer before enabling the RDY interrupts.
> Any possibility of losing interrupts?
>
This fix can cause interrupts to be missed as there will be a race between
writing to DXR and setting of interrupts. I think you can decrement dev->buf_len
before writing to DXR register. This should resolve the original race condition
which you had encountered.
Regards,
Sudhakar
next prev parent reply other threads:[~2010-06-22 12:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-22 7:31 [PATCH] i2c: davinci: Fix race when setting up for TX Jon Povey
[not found] ` <1277191864-5024-1-git-send-email-jon.povey-Ean/AyPsLtfkYMGBc/C6ZA@public.gmane.org>
2010-06-22 12:17 ` Sudhakar Rajashekhara [this message]
-- strict thread matches above, loose matches on Subject: below --
2010-09-16 10:21 Jon Povey
[not found] ` <1284632480-24035-1-git-send-email-jon.povey-Ean/AyPsLtfkYMGBc/C6ZA@public.gmane.org>
2010-09-16 17:37 ` Kevin Hilman
[not found] ` <87pqwda8ub.fsf-1D3HCaltpLuhEniVeURVKkEOCMrvLtNR@public.gmane.org>
2010-09-16 20:28 ` Troy Kisky
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