Re: [PATCH v4 1/3] i3c: master: dw: Report actual GET CCC payload length on success

From: "NG, TZE YEE" <tze.yee.ng@altera.com>
To: Alexandre Mergnat <amergnat@baylibre.com>
Cc: "Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	"Frank Li" <Frank.Li@nxp.com>,
	"NG, ADRIAN HO YIN" <adrian.ho.yin.ng@altera.com>,
	"Felix Gu" <ustc.gu@gmail.com>,
	"Wolfram Sang" <wsa+renesas@sang-engineering.com>,
	"Manikanta Guntupalli" <manikanta.guntupalli@amd.com>,
	"Jorge Marques" <jorge.marques@analog.com>,
	"Sakari Ailus" <sakari.ailus@linux.intel.com>,
	"linux-i3c@lists.infradead.org" <linux-i3c@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Przemysław Gaj" <pgaj@cadence.com>,
	"Tommaso Merciai" <tommaso.merciai.xr@bp.renesas.com>,
	"Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Jarkko Nikula" <jarkko.nikula@linux.intel.com>,
	"imx@lists.linux.dev" <imx@lists.linux.dev>
Subject: Re: [PATCH v4 1/3] i3c: master: dw: Report actual GET CCC payload length on success
Date: Fri, 3 Jul 2026 09:09:24 +0000	[thread overview]
Message-ID: <ca7545d9-9738-42af-aa53-397e8909196e@altera.com> (raw)
In-Reply-To: <178290222674.176638.15906284505119583670.b4-review@b4>

On 1/7/2026 6:37 pm, Alexandre Mergnat wrote:
> [You don't often get email from amergnat@baylibre.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> On Tue, 30 Jun 2026 06:20:25 -0700, tze.yee.ng@altera.com <tze.yee.ng@altera.com> wrote:
>> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
>> index a7593d6efac5..4a984a5be264 100644
>> --- a/drivers/i3c/master/dw-i3c-master.c
>> +++ b/drivers/i3c/master/dw-i3c-master.c
>> @@ -742,7 +742,10 @@ static int dw_i3c_ccc_set(struct dw_i3c_master *master,
>>                dw_i3c_master_dequeue_xfer(master, xfer);
>>
>>        ret = xfer->ret;
>> -     if (xfer->cmds[0].error == RESPONSE_ERROR_IBA_NACK)
>> +     cmd = &xfer->cmds[0];
>> +     if (!ret)
>> +             ccc->dests[0].payload.actual_len = cmd->rx_len;
> 
> In v3 this assignment lived in dw_i3c_ccc_get(); in v4 it has moved into
> dw_i3c_ccc_set(), the write (SET) path. GET CCCs are dispatched to
> dw_i3c_ccc_get() (dw_i3c_master_send_ccc_cmd() calls dw_i3c_ccc_get()
> when ccc->rnw is set), so as it stands actual_len is only written for
> writes - where cmd->rx_len is the count of un-sent bytes, normally 0 -
> and stays 0 for the GET CCCs this commit targets (patch 2 later moves it
> back into dw_i3c_ccc_get()). Was there a reason for moving it in v4?
> As-is it reads like a regression; keeping it in dw_i3c_ccc_get() would
> make the patch match its title and work on its own.
> 
> --
> Alexandre Mergnat <amergnat@baylibre.com>

Hi Alexandre,

You are right — that was an unintentional regression in v4, not a 
deliberate move. actual_len belongs only in dw_i3c_ccc_get(); putting it 
in dw_i3c_ccc_set() left GET CCCs with actual_len == 0. v5 moves it back 
to dw_i3c_ccc_get() so patch 2 matches its title and works on its own. 
Thanks for pointing it out.

Tze Yee
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