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Subject: Re: [PATCH v2] i2c: designware: Only check the first byte for SMBus
 block read length
To:     Sultan Alsawaf <sultan@kerneltoast.com>
Cc:     aaron.ma@canonical.com, admin@kryma.net,
        andriy.shevchenko@linux.intel.com, benjamin.tissoires@redhat.com,
        hdegoede@redhat.com, hn.chen@weidahitech.com, jikos@kernel.org,
        kai.heng.feng@canonical.com, linux-i2c@vger.kernel.org,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        mika.westerberg@linux.intel.com, vicamo.yang@canonical.com,
        wsa@kernel.org
References: <9782f44e-4e01-4e5d-cc50-ab9e2219085c@linux.intel.com>
 <20200616154328.2866-1-sultan@kerneltoast.com>
From:   Jarkko Nikula <jarkko.nikula@linux.intel.com>
Message-ID: <791f22ae-e11a-047f-0a29-a9e27782b0fa@linux.intel.com>
Date:   Wed, 17 Jun 2020 14:08:26 +0300
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On 6/16/20 6:43 PM, Sultan Alsawaf wrote:
> From: Sultan Alsawaf <sultan@kerneltoast.com>
> 
> SMBus block reads can be broken because the read function will just skip
> over bytes it doesn't like until reaching a byte that conforms to the
> length restrictions for block reads. This is problematic when it isn't
> known if the incoming payload is indeed a conforming block read.
> 
> According to the SMBus specification, block reads will only send the
> payload length in the first byte, so we can fix this by only considering
> the first byte in a sequence for block read length purposes.
> 
> Fixes: c3ae106050b9 ("i2c: designware: Implement support for SMBus block read and write")
> Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
> ---
>   drivers/i2c/busses/i2c-designware-master.c | 16 +++++++---------
>   1 file changed, 7 insertions(+), 9 deletions(-)
> 
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>