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Thu, 09 Jan 2020 23:21:27 +0100 Date: Thu, 9 Jan 2020 23:21:25 +0100 From: Peter Seiderer To: Mark Brown Message-ID: <20200109232125.6ecd6cf7@gmx.net> In-Reply-To: <20200109203819.GG3702@sirena.org.uk> References: <20191227152056.9903-1-ps.report@gmx.net> <20200109203819.GG3702@sirena.org.uk> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-suse-linux-gnu) MIME-Version: 1.0 X-Provags-ID: V03:K1:DjtTKNqMyIMnbsmFeAWk2Ki8Sa6uq3PTKJ8OS07PD+CGP4ZkvFP Gr3Ogz07ggS+WCjJtVLhvY3bAARSkUvOWO7BKaaygw2GfFXf6oYMmWkzpOIUgY64y6B4jvZ rGAIVGt7kobbSeBhtxlgRUzAoVyqqni7gQAHqplpqqroUJzbX8G7Ea+jQY5vmdUhz0f3L73 5Nn900wbNP0Pb/ZDHayyA== X-UI-Out-Filterresults: notjunk:1;V03:K0:7TlgbhqVgX0=:6xHe2w0wZonEysTLqGmvsf rI/9rFFBZzvHhvod0lYvlBsGZa1tGrYc31LOXxo8o36xy2czZWsDdpkuHO5eF00sXXRyCp5vP 5ftBQi+K4UtJRlIe66DANLHq9PclZP6+YT/gXC+5eEL0JeSEmDHng27l1Pujj/yzPklUE6a3q G0CDmw8SHKJ6+sDqEOQgQAy3EqDDgHt5M/G8IeWWaKAZebWyrDy1Vek7jaAszfGOT95VcwST3 x7jKYHEebdfTYE/iAJ0x7JbnxcJmBLVgIosO3TdbAVA8Gr6RGVx5Jln0EFaKJG33S9x9hUOgY AiVxefCWpyAER/r9IGthxzEP1f9AR8kApgq/3D54+01zua587XJDVPPF2NPKTjcMi5opQOAbi 2Ad1+5kxxwR1tWDHf0Zu8SWQ2WHIDjIYx4sGU9XJKVnY5T4VGeXTC2E3UqSQhK7Q0RhA9bHdP rkqjf3cJrE+kcsZ1rTW2Hbc+pTuLagpE5aYhe7oXPYq+1kjwG5jA97AWXl+ZagQhgUth22aRa S/Djy2ySXOzFjZHaxU5hc0bPobZ0iE6nuViuEZdJ4DR5NskaEJ1OpLWQsGR0LwGed1VDjgOO6 3juSoMo5ahTQuO4BG0dFJCXwmjM+4fnJd705f5JdJ5VBwPAyN9PfGC8vvj6l4I5zG5Z7qDyyP FnX4C3CfxsS8KhYO/YUkGMKhkcDMcV+dPgZlQ+Gj61SOqxfm8Jp4VfbC1nC2NjAQpzL9XeTnD 3s654iBA53kvu174mrj+0tqETCs3gnWBHGhrO8RBZ1+YZ+g0gn5N5BZMmrbdG3ypvSjULxrDu CqE5z/LI7XSVtQUXvEeGvKa0ChG22DwTjmf84QLqwlDUjhQLFdRsFTjIF6B2rDRvj2o2ld6pW 7Xqa112L0aqHEsa9bL83nqzs/XsvOLt5HPme5AUkuicFs2Esdm9XkVV8xBRLUHBK8mBHBmySH d978Kq4bfpXsglatC4RcSE11OfnX9sn38Ge7RBI5nvsP8QxTAlWDf9fEanlEVWHrFLpZQ0BEc 5RPxs/3vHjMwoj7a6OdlmNpJ+DB8p7zUp7i9MkcfO6L9ej4Si0k9Y/FXvQgxQ1FB6aKo3G8Ag rXc8C0nmsqgwl881lj65gg6JvpXRbfOgrgzq9WS114w1vDQR/Pd4E5Qm+GXba/1XZFJ5br00d Yc75DRkjTQ8wadKGc9FqollVBddk3ddDFgB8P0CufVFV1U5PSOT2Q4MSito8PsMfZJv+jRhsY 2IQ7Cv5GTuXD+uhAi08FKAxJQ5SnCNoEqG45Eknfq8hKMMbH06cYSm1aRykI= Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Takashi Iwai , Liam Girdwood , Annaliese McDermond Subject: Re: [alsa-devel] [PATCH v1] ASoC: tlv320aic32x4: handle regmap_read error gracefully X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" Hello Mark, On Thu, 9 Jan 2020 20:38:19 +0000, Mark Brown wrote: > On Fri, Dec 27, 2019 at 04:20:56PM +0100, Peter Seiderer wrote: > > @@ -338,7 +338,8 @@ static unsigned long clk_aic32x4_div_recalc_rate(struct clk_hw *hw, > > > unsigned int val; > > > - regmap_read(div->regmap, div->reg, &val); > > + if (regmap_read(div->regmap, div->reg, &val)) Unrelated to your question, but I would change this line (on next patch iteration) to (as all other return value checked places for regmap_read in the same file): if (regmap_read(div->regmap, div->reg, &val) < 0) > > + return 0; > > Is this the best fix - shouldn't we be returning an error here? We > don't know what the value programmed into the device actually is so zero > might be wrong, and we still have the risk that the value we read from > the device may be zero if the device is misprogrammed. clk_aic32x4_div_recalc_rate() is used for clk_ops aic32x4_div_ops.recalc_rate, did not check/or see on first sight if there is a error handling on the usage of recalc_rate, but did take a look at some other places where the error handling seems to be to return zero, e.g. sound/soc/codecs/da7219.c sound/soc/intel/skylake/skl-ssp-clk.c, etc. The error occurred with linux-5.3.18, with the earlier versions on regmap_read failure val was (by chance) near 2^31 and evaluated with (val & AIC32X4_DIV_MASK) to 96 (or similar)...but with 5.3.18 evaluated to 0 and the line return DIV_ROUND_UP(parent_rate, val & AIC32X4_DIV_MASK); produced the 'Division by zero'... Regards, Peter _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org https://mailman.alsa-project.org/mailman/listinfo/alsa-devel