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X-IronPort-AV: E=Sophos;i="5.88,349,1635199200"; d="scan'208";a="21927828" Received: from vtuxmail01.tq-net.de ([10.115.0.20]) by mx1.tq-group.com with ESMTP; 07 Feb 2022 10:52:03 +0100 Received: from steina-w.localnet (unknown [10.123.49.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by vtuxmail01.tq-net.de (Postfix) with ESMTPSA id 2696E280065; Mon, 7 Feb 2022 10:52:03 +0100 (CET) From: Alexander Stein To: Laurent Pinchart , Dorota Czaplejewicz Cc: Steve Longerbeam , Philipp Zabel , Mauro Carvalho Chehab , Greg Kroah-Hartman , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Rui Miguel Silva , linux-media@vger.kernel.org, linux-staging@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: (EXT) Re: [PATCH 4/8] media: imx: Fail conversion if pixel format not supported Date: Mon, 07 Feb 2022 10:52:00 +0100 Message-ID: <1905895.usQuhbGJ8B@steina-w> Organization: TQ-Systems GmbH In-Reply-To: <20220205085151.61088d8e.dorota.czaplejewicz@puri.sm> References: <20220204121514.2762676-1-alexander.stein@ew.tq-group.com> <20220205085151.61088d8e.dorota.czaplejewicz@puri.sm> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220207_015206_446310_3325EDEB X-CRM114-Status: GOOD ( 34.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Laurent and Dorota, Am Samstag, 5. Februar 2022, 08:51:51 CET schrieb Dorota Czaplejewicz: > * PGP Signed by an unknown key > > Hi Laurent, > > On Sat, 5 Feb 2022 06:07:37 +0200 > > Laurent Pinchart wrote: > > Hi Alexander and Dorota, > > > > Thank you for the patch. > > > > On Fri, Feb 04, 2022 at 01:15:10PM +0100, Alexander Stein wrote: > > > From: Dorota Czaplejewicz > > > > > > imx_media_find_mbus_format has NULL as a valid return value, > > > therefore the caller should take it into account. > > > > > > Signed-off-by: Dorota Czaplejewicz > > > Signed-off-by: Alexander Stein > > > --- > > > > > > drivers/staging/media/imx/imx-media-utils.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/staging/media/imx/imx-media-utils.c > > > b/drivers/staging/media/imx/imx-media-utils.c index > > > 32aaa2e81bea..e0a256a08c3b 100644 > > > --- a/drivers/staging/media/imx/imx-media-utils.c > > > +++ b/drivers/staging/media/imx/imx-media-utils.c > > > @@ -544,6 +544,9 @@ static int imx56_media_mbus_fmt_to_pix_fmt(struct > > > v4l2_pix_format *pix,> > > > > cc = imx_media_find_mbus_format(code, PIXFMT_SEL_YUV); > > > > The code passed to the function comes from the previous line: > > imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV); > > > > As far as I can tell, this is guaranteed to return a code that will > > result in imx_media_find_mbus_format() returning a non-NULL pointer. > > While I am not well-versed in the implicit code style of the kernel, I > decided to leave it in because it makes the code more locally legible. With > a check here, even a non-functional one, there's no need to understand the > internals of `imx_media_find_mbus_format` that are only implicit. That > makes the code less surprising when interested only in the outer function. > > The other advantage of a check is becoming robust against future changes to > `imx_media_find_mbus_format` itself. > > I don't have a strong preference about keeping or leaving this patch, but if > this check was there in the first place, I wouldn't have spent time trying > to figure out whether there's a bug here. Laurent, thanks for your feedback. I'm on Dorota's side here. While you are right that the code from imx_media_enum_mbus_formats(&code, 0, PIXFMT_SEL_YUV); is guaranteed to return something. I don't lnek this implicit assumption over 2 function calls. Better be safe than sorry. For that reason code should be initialized as well. Will create a patch for that. Regards, Alexander _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel