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Wed, 14 Jul 2021 02:10:51 +0000 From: =?iso-2022-jp?B?GyRCQ1NFRBsoQiAbJEI1QU40GyhC?= To: Mark Brown CC: =?iso-2022-jp?B?GyRCQ1NFRBsoQiAbJEI1QU40GyhC?= , Philipp Zabel , "linux-spi@vger.kernel.org" , =?iso-2022-jp?B?GyRCP2VDKxsoQiAbJEIybU01GyhC?= , =?iso-2022-jp?B?GyRCXFQ+PhsoQiAbJEI4JhsoQg==?= Subject: Re: [PATCH] spi: spi-cadence-quadspi: Fix division by zero warning Thread-Topic: [PATCH] spi: spi-cadence-quadspi: Fix division by zero warning Thread-Index: AQHXd7fwKzEQWTvWzEqH2Qm18vEKNatA1OMAgADmmQA= Date: Wed, 14 Jul 2021 02:10:51 +0000 Message-ID: <3b9745c1-ec32-793f-41c2-98c9f60057cc@nskint.co.jp> References: <1406d756-1edb-6294-116b-91c7a9d29b71@nskint.co.jp> <20210713122528.GB4098@sirena.org.uk> In-Reply-To: <20210713122528.GB4098@sirena.org.uk> Accept-Language: ja-JP, en-US Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 authentication-results: kernel.org; dkim=none (message not signed) header.d=none;kernel.org; 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charset="iso-2022-jp" Content-ID: <4831677C6594BA4C8BD4893DB488749F@jpnprd01.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nskint.co.jp X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: OSZPR01MB7004.jpnprd01.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 55bfe9d1-0934-4341-def5-08d9466c9ac8 X-MS-Exchange-CrossTenant-originalarrivaltime: 14 Jul 2021 02:10:51.5937 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 727455a2-9822-4451-819f-f03e059d1a55 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: fP4O9EO3oZ/QLvaKvT35C2NoROqjPGePg+ZitjnT4RrthmEFehBLJWscF5TF1yKUIwY5G/Jh+3K9WpAgWlXHHA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: OSAPR01MB2868 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org On 2021/07/13 21:25, Mark Brown wrote: > On Tue, Jul 13, 2021 at 07:23:12AM +0000, Yoshitaka Ikeda wrote: >> Fix below division by zero warning: >> - Added an if statement because buswidth can be zero, resulting in divis= ion by zero. >> - The modified code was based on another driver (atmel-quadspi). >> >> [ 0.795337] Division by zero in kernel. >> [ 0.797878] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.12.0-xxx-xxxx= + #1 >> [ 0.803782] Hardware name: Altera SOCFPGA >> [ 0.806481] Backtrace: >> [ 0.807628] [<807fd2b0>] (dump_backtrace) from [<807fd554>] (show_sta= ck+0x20/0x24) >=20 > Please think hard before including complete backtraces in upstream > reports, they are very large and contain almost no useful information > relative to their size so often obscure the relevant content in your > message. If part of the backtrace is usefully illustrative (it often is > for search engines if nothing else) then it's usually better to pull out > the relevant sections. Thanks for the reply. Indeed, I too think that the tracing part should be limited to the useful r= ange. I would like to modify the tracing part as follows and repost it. Do you think I should narrow it down further or do you think it is too narr= ow? Or unnecessary? [ 0.795337] Division by zero in kernel. : [ 0.834051] [<807fd40c>] (__div0) from [<804e1acc>] (Ldiv0+0x8/0x10) [ 0.839097] [<805f0710>] (cqspi_exec_mem_op) from [<805edb4c>] (spi_mem_= exec_op+0x3b0/0x3f8)