linux-kernel - Re: [PATCH v2 2/4] i2c: designware: Ensure tx_buf

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Message-ID: <20200917144532.GO3956970@smile.fi.intel.com>
Date:   Thu, 17 Sep 2020 17:45:32 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc:     Sultan Alsawaf <sultan@...neltoast.com>, linux-i2c@...r.kernel.org,
        jikos@...nel.org, aaron.ma@...onical.com, admin@...ma.net,
        benjamin.tissoires@...hat.com, hdegoede@...hat.com,
        hn.chen@...dahitech.com, kai.heng.feng@...onical.com,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        mika.westerberg@...ux.intel.com, vicamo.yang@...onical.com,
        wsa@...nel.org
Subject: Re: [PATCH v2 2/4] i2c: designware: Ensure tx_buf_len is nonzero for
 SMBus block reads

On Thu, Sep 17, 2020 at 04:44:18PM +0300, Jarkko Nikula wrote:
> On 9/17/20 8:22 AM, Sultan Alsawaf wrote:
> > From: Sultan Alsawaf <sultan@...neltoast.com>
> > 
> > The point of adding a byte to len in i2c_dw_recv_len() is to make sure
> > that tx_buf_len is nonzero, so that i2c_dw_xfer_msg() can let the i2c
> > controller know that the i2c transaction can end. Otherwise, the i2c
> > controller will think that the transaction can never end for block
> > reads, which results in the stop-detection bit never being set and thus
> > the transaction timing out.
> > 
> > Adding a byte to len is not a reliable way to do this though; sometimes
> > it lets tx_buf_len become zero, which results in the scenario described
> > above. Therefore, just directly ensure tx_buf_len cannot be zero to fix
> > the issue.
> > 
> > Fixes: c3ae106050b9 ("i2c: designware: Implement support for SMBus block read and write")
> > Signed-off-by: Sultan Alsawaf <sultan@...neltoast.com>
> > ---
> >   drivers/i2c/busses/i2c-designware-master.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> Were other patches in series dropped somewhere? I received only this.

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-- 
With Best Regards,
Andy Shevchenko