From: David Laight <David.Laight@ACULAB.COM> To: "'Uwe Kleine-König'" <u.kleine-koenig@pengutronix.de> Cc: 'Christian Eggers' <ceggers@arri.de>, Oleksij Rempel <linux@rempel-privat.de>, Shawn Guo <shawnguo@kernel.org>, Sascha Hauer <s.hauer@pengutronix.de>, Fabio Estevam <festevam@gmail.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "stable@vger.kernel.org" <stable@vger.kernel.org>, NXP Linux Team <linux-imx@nxp.com>, Pengutronix Kernel Team <kernel@pengutronix.de>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org> Subject: RE: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag Date: Tue, 6 Oct 2020 12:52:13 +0000 [thread overview] Message-ID: <0ccbfc8fe2a44796a61e59d1527fe6be@AcuMS.aculab.com> (raw) In-Reply-To: <20201006124602.oxfyzb3atoju7sva@pengutronix.de> From: Uwe Kleine-König > Sent: 06 October 2020 13:46 ... > > > +static void i2c_imx_clear_irq(struct imx_i2c_struct *i2c_imx, unsigned int bits) > > > +{ > > > + unsigned int temp; > > > + > > > + /* > > > + * i2sr_clr_opcode is the value to clear all interrupts. > > > + * Here we want to clear only <bits>, so we write > > > + * ~i2sr_clr_opcode with just <bits> toggled. > > > + */ > > > + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ bits; > > > + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); > > > +} > > > > That looks either wrong or maybe just overcomplicated. > > Why isn't: > > imx_i2c_write_reg(bits, i2c_imx, IMX_I2C_I2SR); > > enough? > > Your question suggests you either didn't read the comment or the comment > is not good enough. Maybe once you understood the complication (see > Christian's mail) you could suggest a better wording? Maybe we have to > mention that this handles both W1C and W0C. Yes, the comment should just say that some devices are W1C and other W0C. It isn't obvious from that code fragment at all. Now for the 3rd variant which zeros the bits when they are read :-) David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
WARNING: multiple messages have this Message-ID (diff)
From: David Laight <David.Laight@ACULAB.COM> To: "'Uwe Kleine-König'" <u.kleine-koenig@pengutronix.de> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>, 'Christian Eggers' <ceggers@arri.de>, Sascha Hauer <s.hauer@pengutronix.de>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "stable@vger.kernel.org" <stable@vger.kernel.org>, Oleksij Rempel <linux@rempel-privat.de>, NXP Linux Team <linux-imx@nxp.com>, Fabio Estevam <festevam@gmail.com>, Shawn Guo <shawnguo@kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org> Subject: RE: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag Date: Tue, 6 Oct 2020 12:52:13 +0000 [thread overview] Message-ID: <0ccbfc8fe2a44796a61e59d1527fe6be@AcuMS.aculab.com> (raw) In-Reply-To: <20201006124602.oxfyzb3atoju7sva@pengutronix.de> From: Uwe Kleine-König > Sent: 06 October 2020 13:46 ... > > > +static void i2c_imx_clear_irq(struct imx_i2c_struct *i2c_imx, unsigned int bits) > > > +{ > > > + unsigned int temp; > > > + > > > + /* > > > + * i2sr_clr_opcode is the value to clear all interrupts. > > > + * Here we want to clear only <bits>, so we write > > > + * ~i2sr_clr_opcode with just <bits> toggled. > > > + */ > > > + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ bits; > > > + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); > > > +} > > > > That looks either wrong or maybe just overcomplicated. > > Why isn't: > > imx_i2c_write_reg(bits, i2c_imx, IMX_I2C_I2SR); > > enough? > > Your question suggests you either didn't read the comment or the comment > is not good enough. Maybe once you understood the complication (see > Christian's mail) you could suggest a better wording? Maybe we have to > mention that this handles both W1C and W0C. Yes, the comment should just say that some devices are W1C and other W0C. It isn't obvious from that code fragment at all. Now for the 3rd variant which zeros the bits when they are read :-) David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-10-06 12:52 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-02 15:23 [PATCH v2 0/3] i2c: imx: Fix handling of arbitration loss Christian Eggers 2020-10-02 15:23 ` Christian Eggers 2020-10-02 15:23 ` [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag Christian Eggers 2020-10-02 15:23 ` Christian Eggers 2020-10-05 8:05 ` Krzysztof Kozlowski 2020-10-05 8:05 ` Krzysztof Kozlowski 2020-10-06 6:05 ` Uwe Kleine-König 2020-10-06 6:05 ` Uwe Kleine-König 2020-10-06 10:51 ` [PATCH v3 0/3] i2c: imx: Fix handling of arbitration loss Christian Eggers 2020-10-06 10:51 ` Christian Eggers 2020-10-06 10:51 ` [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag Christian Eggers 2020-10-06 10:51 ` Christian Eggers 2020-10-06 12:06 ` David Laight 2020-10-06 12:06 ` David Laight 2020-10-06 12:30 ` Christian Eggers 2020-10-06 12:30 ` Christian Eggers 2020-10-06 12:46 ` Uwe Kleine-König 2020-10-06 12:46 ` Uwe Kleine-König 2020-10-06 12:52 ` David Laight [this message] 2020-10-06 12:52 ` David Laight 2020-10-06 10:51 ` [PATCH v3 2/3] i2c: imx: Check for I2SR_IAL after every byte Christian Eggers 2020-10-06 10:51 ` Christian Eggers 2020-10-06 10:51 ` [PATCH v3 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost Christian Eggers 2020-10-06 10:51 ` Christian Eggers 2020-10-02 15:23 ` [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte Christian Eggers 2020-10-02 15:23 ` Christian Eggers 2020-10-05 8:07 ` Krzysztof Kozlowski 2020-10-05 8:07 ` Krzysztof Kozlowski 2020-10-05 9:25 ` Christian Eggers 2020-10-05 9:25 ` Christian Eggers 2020-10-02 15:23 ` [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost Christian Eggers 2020-10-02 15:23 ` Christian Eggers 2020-10-05 8:16 ` Krzysztof Kozlowski 2020-10-05 8:16 ` Krzysztof Kozlowski
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