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

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Message-ID: <4698b23c-7af6-3f44-975d-b1f692ae3f00@linux.intel.com>
Date:   Thu, 17 Sep 2020 16:44:18 +0300
From:   Jarkko Nikula <jarkko.nikula@...ux.intel.com>
To:     Sultan Alsawaf <sultan@...neltoast.com>, linux-i2c@...r.kernel.org
Cc:     jikos@...nel.org, aaron.ma@...onical.com, admin@...ma.net,
        andriy.shevchenko@...ux.intel.com, 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 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.

Jarkko