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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: AS8PR04MB8404.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: fa185540-d96f-446b-5416-08da7535abdb X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Aug 2022 09:51:00.3184 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 05dogl+fq2W+pUHKFj8aLGC4gtosAm/XplOkF/l1fPCnFViv5j1wU6ddDUSQDR6xQlkhhDalPSrd4yhz2ijmoA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR04MB5513 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Subject: Re: [PATCH] tty: serial: imx: initialize > peripheral_config/peripheral_size for sdma config >=20 > On Wed, Aug 03, 2022 at 09:15:58AM +0000, Sherry Sun wrote: > > > On 03.08.22 08:57, Sherry Sun wrote: > > > > Since commit 824a0a02cd74 ("dmaengine: imx-sdma: Add multi fifo > > > > support") adds the use of > > > > dma_slave_config->peripheral_config/peripheral_size to sdma > > > > driver, the client drivers like uart need to initialize the > > > > peripheral_config/peripheral_size for sdma, otherwise, the random > > > > value of local variable slave_config may cause unexpected > > > peripheral_config and make sdma mess up. > > > > > > > > > > If this a fix, please add a Fixes: tag. I am not sure it is though, s= ee below. > > > > Hi Ahmad, thanks for the comments. > > I don't think this patch is a fix for a specific commit, so we don't ne= ed the > Fixes tag. > > > > > > > > > Signed-off-by: Sherry Sun > > > > --- > > > > drivers/tty/serial/imx.c | 4 ++++ > > > > 1 file changed, 4 insertions(+) > > > > > > > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > > > > index > > > > 522445a8f666..bb8c2a712e94 100644 > > > > --- a/drivers/tty/serial/imx.c > > > > +++ b/drivers/tty/serial/imx.c > > > > @@ -1320,6 +1320,8 @@ static int imx_uart_dma_init(struct imx_port > > > > *sport) > > > > > > This function starts with > > > > > > struct dma_slave_config slave_config =3D {}; > > > > > > > slave_config.src_addr_width =3D DMA_SLAVE_BUSWIDTH_1_BYTE; > > > > /* one byte less than the watermark level to enable the aging > > > > timer > > > */ > > > > slave_config.src_maxburst =3D RXTL_DMA - 1; > > > > + slave_config.peripheral_config =3D NULL; > > > > + slave_config.peripheral_size =3D 0; > > > > > > So these are already zero-initialized. > > > > I am not sure actually, I think initialize a struct with {} cannot > > guarantee that all members are initialized to 0, it may depend on the > > compiler. >=20 > I'm sure and even reverified in my C book[1]. >=20 > struct mystruct variable =3D {}; >=20 > results in all components being initialized to their default initial valu= e (which > is 0 for numbers and NULL for pointers). This works for automatic variabl= es > since "Standard C" which should cover everthing that is capable to compil= e > today's kernel. >=20 > Best regards > Uwe >=20 > [1] C - A Reference Manual, 978-0130895929 >=20 Hi Uwe, wow, this really resolved my confusion, thanks a lot for your confi= rmation! ^_^ Best regards Sherry