From: Tejun Heo <tj@kernel.org>
To: Stuart MENEFY <stuart.menefy@st.com>
Cc: linux-ide@vger.kernel.org
Subject: Re: [PATCH] libata: Keep shadow last_ctl up to date during resets
Date: Wed, 11 Mar 2009 16:42:57 +0900 [thread overview]
Message-ID: <49B76B81.9000407@kernel.org> (raw)
In-Reply-To: <49B65125.7030201@st.com>
Hello,
Stuart MENEFY wrote:
> libata keeps a shadow copy of the ATA CTL register (which is write only),
> and only writes to the hardware when the required value doesn't match
> the shadow. However this copy wasn't being maintained when performing
> reset functions. This could cause problems for the first operation after
> a reset when the correct value might not be written to the CTL register.
>
> This problem was observed when hotplugging a drive: the identify command
> was being issued with interrupts enabled, when they should have been
> disabled.
>
> Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Nice catch. Maybe a nice addition would be a ata_sff_write_to_ctl()
or something which always does the right thing.
Acked-by: Tejun Heo <tj@kernel.org>
Thanks.
--
tejun
next prev parent reply other threads:[~2009-03-11 7:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-10 11:38 [PATCH] libata: Keep shadow last_ctl up to date during resets Stuart MENEFY
2009-03-11 7:42 ` Tejun Heo [this message]
2009-03-11 12:28 ` Mark Lord
2009-03-11 13:11 ` Tejun Heo
2009-03-13 18:58 ` Jeff Garzik
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