Re: [PATCH v2 1/2] spi: Add Renesas R-Car Gen3 RPC SPI controller driver

From: Marek Vasut <marek.vasut@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>, masonccyang@mxic.com.tw
Cc: Boris Brezillon <boris.brezillon@bootlin.com>,
	Mark Brown <broonie@kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Simon Horman <horms@verge.net.au>,
	juliensu@mxic.com.tw,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	linux-spi <linux-spi@vger.kernel.org>,
	zhengxunli@mxic.com.tw
Subject: Re: [PATCH v2 1/2] spi: Add Renesas R-Car Gen3 RPC SPI controller driver
Date: Thu, 6 Dec 2018 10:14:17 +0100	[thread overview]
Message-ID: <915d772b-616b-9f2e-8f4e-16d9d349e0cf@gmail.com> (raw)
In-Reply-To: <CAMuHMdWspyRq_K2Vd6Xk2tqft-oUoMvVhj-zKS-fuhv_edXb8Q@mail.gmail.com>

On 12/06/2018 10:12 AM, Geert Uytterhoeven wrote:
> Hi Mason,
> 
> On Thu, Dec 6, 2018 at 8:31 AM <masonccyang@mxic.com.tw> wrote:
>>>>> Re: [PATCH v2 1/2] spi: Add Renesas R-Car Gen3 RPC SPI controller driver
>>>>>
>>>>> On 12/03/2018 10:18 AM, Mason Yang wrote:
>>>>>> Add a driver for Renesas R-Car Gen3 RPC SPI controller.
>>>>>>
>>>>>> Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
> 
>>>>>> +   xfercnt = xferpos;
>>>>>> +   rpc->xferlen = xfer[--xferpos].len;
>>>>>> +   rpc->cmd = RPC_SMCMR_CMD(((u8 *)xfer[0].tx_buf)[0]);
>>>>>
>>>>> Is the cast needed ?
>>>>
>>>> yes!
>>>
>>> Why ?
>>
>> Get a compiler warning due to tx_bug is void *, as Geert replied.
>>
>> Using get_unaligned(), patched code would be
>> ---------------------------------------------------------------
>>  rpc->cmd = RPC_SMCMR_CMD(get_unaligned((u8 *)xfer[0].tx_buf));
>> ----------------------------------------------------------------
> 
> Using get_unaligned(0 is a bit strange for accessing a single byte quantity.
> Please keep the normal pointer dereference (including the cast).

Oh, right, for single bytes this is OK.

-- 
Best regards,
Marek Vasut