* [PATCH v2 0/3] i2c: imx: Fix handling of arbitration loss @ 2020-10-02 15:23 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel Changes in v2: --------------- - Don't accidently clear additional status flags on Vybrid (reported by Uwe Kleine-Koenig) On my (noisy) system, I2C arbitration losses happen quite often. In it's current implementation, the IAL flag is partly handled, but has a number of shortcomings: 1. The driver runs unnecessarily in a timeout when waiting for an interrupt. 2. The driver performs 500 ms busy-waiting without any value. 3. Arbitration loss errors may be reported one transfer later than they occured. Best regards Christian ^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH v2 0/3] i2c: imx: Fix handling of arbitration loss @ 2020-10-02 15:23 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-arm-kernel, linux-kernel, NXP Linux Team, Pengutronix Kernel Team, linux-i2c Changes in v2: --------------- - Don't accidently clear additional status flags on Vybrid (reported by Uwe Kleine-Koenig) On my (noisy) system, I2C arbitration losses happen quite often. In it's current implementation, the IAL flag is partly handled, but has a number of shortcomings: 1. The driver runs unnecessarily in a timeout when waiting for an interrupt. 2. The driver performs 500 ms busy-waiting without any value. 3. Arbitration loss errors may be reported one transfer later than they occured. Best regards Christian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-02 15:23 ` Christian Eggers @ 2020-10-02 15:23 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, Christian Eggers, stable According to the "VFxxx Controller Reference Manual" (and the comment block starting at line 97), Vybrid requires writing a one for clearing an interrupt flag. Syncing the method for clearing I2SR_IIF in i2c_imx_isr(). Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 0ab5381aa012..34648df7f1a6 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -424,7 +424,12 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a /* check for arbitration lost */ if (temp & I2SR_IAL) { - temp &= ~I2SR_IAL; + /* + * i2sr_clr_opcode is the value to clear all interrupts. + * Here we want to clear only I2SR_IAL, so we write + * ~i2sr_clr_opcode with just the I2SR_IAL bit toggled. + */ + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IAL; imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); return -EAGAIN; } @@ -623,8 +628,12 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id) if (temp & I2SR_IIF) { /* save status register */ i2c_imx->i2csr = temp; - temp &= ~I2SR_IIF; - temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF); + /* + * i2sr_clr_opcode is the value to clear all interrupts. + * Here we want to clear only I2SR_IIF, so we write + * ~i2sr_clr_opcode with just the I2SR_IIF bit toggled. + */ + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IIF; imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); wake_up(&i2c_imx->queue); return IRQ_HANDLED; -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-02 15:23 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, Christian Eggers, linux-arm-kernel, linux-i2c According to the "VFxxx Controller Reference Manual" (and the comment block starting at line 97), Vybrid requires writing a one for clearing an interrupt flag. Syncing the method for clearing I2SR_IIF in i2c_imx_isr(). Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 0ab5381aa012..34648df7f1a6 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -424,7 +424,12 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a /* check for arbitration lost */ if (temp & I2SR_IAL) { - temp &= ~I2SR_IAL; + /* + * i2sr_clr_opcode is the value to clear all interrupts. + * Here we want to clear only I2SR_IAL, so we write + * ~i2sr_clr_opcode with just the I2SR_IAL bit toggled. + */ + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IAL; imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); return -EAGAIN; } @@ -623,8 +628,12 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id) if (temp & I2SR_IIF) { /* save status register */ i2c_imx->i2csr = temp; - temp &= ~I2SR_IIF; - temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF); + /* + * i2sr_clr_opcode is the value to clear all interrupts. + * Here we want to clear only I2SR_IIF, so we write + * ~i2sr_clr_opcode with just the I2SR_IIF bit toggled. + */ + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IIF; imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); wake_up(&i2c_imx->queue); return IRQ_HANDLED; -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 34+ messages in thread
* Re: [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-02 15:23 ` Christian Eggers @ 2020-10-05 8:05 ` Krzysztof Kozlowski -1 siblings, 0 replies; 34+ messages in thread From: Krzysztof Kozlowski @ 2020-10-05 8:05 UTC (permalink / raw) To: Christian Eggers Cc: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König, Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, stable On Fri, Oct 02, 2020 at 05:23:03PM +0200, Christian Eggers wrote: > According to the "VFxxx Controller Reference Manual" (and the comment > block starting at line 97), Vybrid requires writing a one for clearing > an interrupt flag. Syncing the method for clearing I2SR_IIF in > i2c_imx_isr(). > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@kernel.org> The I2C on Vybrid VF500 still works fine. I did not test this actual condition (arbitration) but only a regular I2C driver (BQ27xxx fuel gauge). Best regards, Krzysztof ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-05 8:05 ` Krzysztof Kozlowski 0 siblings, 0 replies; 34+ messages in thread From: Krzysztof Kozlowski @ 2020-10-05 8:05 UTC (permalink / raw) To: Christian Eggers Cc: Shawn Guo, Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Pengutronix Kernel Team, Uwe Kleine-König, Fabio Estevam, linux-arm-kernel, linux-i2c On Fri, Oct 02, 2020 at 05:23:03PM +0200, Christian Eggers wrote: > According to the "VFxxx Controller Reference Manual" (and the comment > block starting at line 97), Vybrid requires writing a one for clearing > an interrupt flag. Syncing the method for clearing I2SR_IIF in > i2c_imx_isr(). > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@kernel.org> The I2C on Vybrid VF500 still works fine. I did not test this actual condition (arbitration) but only a regular I2C driver (BQ27xxx fuel gauge). Best regards, Krzysztof _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-02 15:23 ` Christian Eggers @ 2020-10-06 6:05 ` Uwe Kleine-König -1 siblings, 0 replies; 34+ messages in thread From: Uwe Kleine-König @ 2020-10-06 6:05 UTC (permalink / raw) To: Christian Eggers Cc: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, linux-arm-kernel, linux-i2c [-- Attachment #1: Type: text/plain, Size: 1771 bytes --] On Fri, Oct 02, 2020 at 05:23:03PM +0200, Christian Eggers wrote: > According to the "VFxxx Controller Reference Manual" (and the comment > block starting at line 97), Vybrid requires writing a one for clearing > an interrupt flag. Syncing the method for clearing I2SR_IIF in > i2c_imx_isr(). > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index 0ab5381aa012..34648df7f1a6 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -424,7 +424,12 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a > > /* check for arbitration lost */ > if (temp & I2SR_IAL) { > - temp &= ~I2SR_IAL; > + /* > + * i2sr_clr_opcode is the value to clear all interrupts. > + * Here we want to clear only I2SR_IAL, so we write > + * ~i2sr_clr_opcode with just the I2SR_IAL bit toggled. > + */ > + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IAL; > imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); > return -EAGAIN; Could we please move clearing an irq to a dedicated function? Such that it looks like: /* check for arbitration lost */ if (temp & I2SR_IAL) { i2c_imx_clear_irq(i2c_imx, I2SR_IAL); return -EAGAIN; } Then you also don't need to duplicate the describing comment but just add it to the implementation of i2c_imx_clear_irq(). Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ | [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --] ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-06 6:05 ` Uwe Kleine-König 0 siblings, 0 replies; 34+ messages in thread From: Uwe Kleine-König @ 2020-10-06 6:05 UTC (permalink / raw) To: Christian Eggers Cc: Shawn Guo, Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Pengutronix Kernel Team, Fabio Estevam, linux-arm-kernel, linux-i2c [-- Attachment #1.1: Type: text/plain, Size: 1771 bytes --] On Fri, Oct 02, 2020 at 05:23:03PM +0200, Christian Eggers wrote: > According to the "VFxxx Controller Reference Manual" (and the comment > block starting at line 97), Vybrid requires writing a one for clearing > an interrupt flag. Syncing the method for clearing I2SR_IIF in > i2c_imx_isr(). > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index 0ab5381aa012..34648df7f1a6 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -424,7 +424,12 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a > > /* check for arbitration lost */ > if (temp & I2SR_IAL) { > - temp &= ~I2SR_IAL; > + /* > + * i2sr_clr_opcode is the value to clear all interrupts. > + * Here we want to clear only I2SR_IAL, so we write > + * ~i2sr_clr_opcode with just the I2SR_IAL bit toggled. > + */ > + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IAL; > imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); > return -EAGAIN; Could we please move clearing an irq to a dedicated function? Such that it looks like: /* check for arbitration lost */ if (temp & I2SR_IAL) { i2c_imx_clear_irq(i2c_imx, I2SR_IAL); return -EAGAIN; } Then you also don't need to duplicate the describing comment but just add it to the implementation of i2c_imx_clear_irq(). Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ | [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --] [-- Attachment #2: Type: text/plain, Size: 176 bytes --] _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH v3 0/3] i2c: imx: Fix handling of arbitration loss 2020-10-06 6:05 ` Uwe Kleine-König @ 2020-10-06 10:51 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel On Tuesday, 6 October 2020, 08:05:28 CEST, Uwe Kleine-König wrote: > Could we please move clearing an irq to a dedicated function? Such that > it looks like: > > /* check for arbitration lost */ > if (temp & I2SR_IAL) { > i2c_imx_clear_irq(i2c_imx, I2SR_IAL); > return -EAGAIN; > } done Changes in v2: --------------- - Don't accidently clear additional status flags on Vybrid (reported by Uwe Kleine-Koenig) Changes in v3: --------------- - dedicated function for clearing an irq ^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH v3 0/3] i2c: imx: Fix handling of arbitration loss @ 2020-10-06 10:51 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-arm-kernel, linux-kernel, NXP Linux Team, Pengutronix Kernel Team, linux-i2c On Tuesday, 6 October 2020, 08:05:28 CEST, Uwe Kleine-König wrote: > Could we please move clearing an irq to a dedicated function? Such that > it looks like: > > /* check for arbitration lost */ > if (temp & I2SR_IAL) { > i2c_imx_clear_irq(i2c_imx, I2SR_IAL); > return -EAGAIN; > } done Changes in v2: --------------- - Don't accidently clear additional status flags on Vybrid (reported by Uwe Kleine-Koenig) Changes in v3: --------------- - dedicated function for clearing an irq _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-06 10:51 ` Christian Eggers @ 2020-10-06 10:51 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, Christian Eggers, stable According to the "VFxxx Controller Reference Manual" (and the comment block starting at line 97), Vybrid requires writing a one for clearing an interrupt flag. Syncing the method for clearing I2SR_IIF in i2c_imx_isr(). Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 0ab5381aa012..745f4071155a 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -412,6 +412,19 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) dma->chan_using = NULL; } +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); +} + static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool atomic) { unsigned long orig_jiffies = jiffies; @@ -424,8 +437,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a /* check for arbitration lost */ if (temp & I2SR_IAL) { - temp &= ~I2SR_IAL; - imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); + i2c_imx_clear_irq(i2c_imx, I2SR_IAL); return -EAGAIN; } @@ -623,9 +635,7 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id) if (temp & I2SR_IIF) { /* save status register */ i2c_imx->i2csr = temp; - temp &= ~I2SR_IIF; - temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF); - imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); + i2c_imx_clear_irq(i2c_imx, I2SR_IIF); wake_up(&i2c_imx->queue); return IRQ_HANDLED; } -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-06 10:51 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, Christian Eggers, linux-arm-kernel, linux-i2c According to the "VFxxx Controller Reference Manual" (and the comment block starting at line 97), Vybrid requires writing a one for clearing an interrupt flag. Syncing the method for clearing I2SR_IIF in i2c_imx_isr(). Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 0ab5381aa012..745f4071155a 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -412,6 +412,19 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) dma->chan_using = NULL; } +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); +} + static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool atomic) { unsigned long orig_jiffies = jiffies; @@ -424,8 +437,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a /* check for arbitration lost */ if (temp & I2SR_IAL) { - temp &= ~I2SR_IAL; - imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); + i2c_imx_clear_irq(i2c_imx, I2SR_IAL); return -EAGAIN; } @@ -623,9 +635,7 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id) if (temp & I2SR_IIF) { /* save status register */ i2c_imx->i2csr = temp; - temp &= ~I2SR_IIF; - temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF); - imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); + i2c_imx_clear_irq(i2c_imx, I2SR_IIF); wake_up(&i2c_imx->queue); return IRQ_HANDLED; } -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 34+ messages in thread
* RE: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-06 10:51 ` Christian Eggers @ 2020-10-06 12:06 ` David Laight -1 siblings, 0 replies; 34+ messages in thread From: David Laight @ 2020-10-06 12:06 UTC (permalink / raw) To: 'Christian Eggers', Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, stable From: Christian Eggers > Sent: 06 October 2020 11:52 > > According to the "VFxxx Controller Reference Manual" (and the comment > block starting at line 97), Vybrid requires writing a one for clearing > an interrupt flag. Syncing the method for clearing I2SR_IIF in > i2c_imx_isr(). > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index 0ab5381aa012..745f4071155a 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -412,6 +412,19 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) > dma->chan_using = NULL; > } > > +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? More usually you just write back the read value of such 'write 1 to clear' status registers and then act on all the set bits. That ensures you clear all interrupts that were pending. If you need to avoid writes of bits that aren't in the 'clear all interrupts' value then you just need: bits &= i2c_imx->hwdata->i2sr_clr_opcode; prior to the write. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) ^ permalink raw reply [flat|nested] 34+ messages in thread
* RE: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-06 12:06 ` David Laight 0 siblings, 0 replies; 34+ messages in thread From: David Laight @ 2020-10-06 12:06 UTC (permalink / raw) To: 'Christian Eggers', Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, linux-arm-kernel, linux-i2c From: Christian Eggers > Sent: 06 October 2020 11:52 > > According to the "VFxxx Controller Reference Manual" (and the comment > block starting at line 97), Vybrid requires writing a one for clearing > an interrupt flag. Syncing the method for clearing I2SR_IIF in > i2c_imx_isr(). > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++----- > 1 file changed, 15 insertions(+), 5 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index 0ab5381aa012..745f4071155a 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -412,6 +412,19 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) > dma->chan_using = NULL; > } > > +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? More usually you just write back the read value of such 'write 1 to clear' status registers and then act on all the set bits. That ensures you clear all interrupts that were pending. If you need to avoid writes of bits that aren't in the 'clear all interrupts' value then you just need: bits &= i2c_imx->hwdata->i2sr_clr_opcode; prior to the write. 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 ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-06 12:06 ` David Laight @ 2020-10-06 12:30 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 12:30 UTC (permalink / raw) To: David Laight Cc: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König, Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, stable, Krzysztof Kozlowski Hi David, On Tuesday, 6 October 2020, 14:06:36 CEST, David Laight wrote: > From: Christian Eggers > > +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. Yes, it looks so. > Why isn't: > imx_i2c_write_reg(bits, i2c_imx, IMX_I2C_I2SR); > enough? i.MX requires W1C and Vybrid requires W0C in order to clear status bits. > More usually you just write back the read value of such > 'write 1 to clear' status registers and then act on all > the set bits. This pattern has been suggested by Uwe Klein-Koenig. It works because write access to read-only register bits is ignored, independent whether 0 or 1 is written. W0C is quite unusual, but I didn't design the hardware... The pattern ensures that not accidentally more status bits are cleared than desired. > That ensures you clear all interrupts that were pending. I think that Uwe's intention was not clearing bits which are not handled at this place. Otherwise events may get lost. > If you need to avoid writes of bits that aren't in the > 'clear all interrupts' value then you just need: > bits &= i2c_imx->hwdata->i2sr_clr_opcode; > prior to the write. I think this wouldn't fit the W0C case for Vybrid. Best regards Christian ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-06 12:30 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 12:30 UTC (permalink / raw) To: David Laight Cc: Krzysztof Kozlowski, Shawn Guo, Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Pengutronix Kernel Team, Uwe Kleine-König, Fabio Estevam, linux-arm-kernel, linux-i2c Hi David, On Tuesday, 6 October 2020, 14:06:36 CEST, David Laight wrote: > From: Christian Eggers > > +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. Yes, it looks so. > Why isn't: > imx_i2c_write_reg(bits, i2c_imx, IMX_I2C_I2SR); > enough? i.MX requires W1C and Vybrid requires W0C in order to clear status bits. > More usually you just write back the read value of such > 'write 1 to clear' status registers and then act on all > the set bits. This pattern has been suggested by Uwe Klein-Koenig. It works because write access to read-only register bits is ignored, independent whether 0 or 1 is written. W0C is quite unusual, but I didn't design the hardware... The pattern ensures that not accidentally more status bits are cleared than desired. > That ensures you clear all interrupts that were pending. I think that Uwe's intention was not clearing bits which are not handled at this place. Otherwise events may get lost. > If you need to avoid writes of bits that aren't in the > 'clear all interrupts' value then you just need: > bits &= i2c_imx->hwdata->i2sr_clr_opcode; > prior to the write. I think this wouldn't fit the W0C case for Vybrid. Best regards Christian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-06 12:06 ` David Laight @ 2020-10-06 12:46 ` Uwe Kleine-König -1 siblings, 0 replies; 34+ messages in thread From: Uwe Kleine-König @ 2020-10-06 12:46 UTC (permalink / raw) To: David Laight Cc: 'Christian Eggers', Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, linux-arm-kernel, linux-i2c [-- Attachment #1: Type: text/plain, Size: 1949 bytes --] On Tue, Oct 06, 2020 at 12:06:36PM +0000, David Laight wrote: > From: Christian Eggers > > Sent: 06 October 2020 11:52 > > > > According to the "VFxxx Controller Reference Manual" (and the comment > > block starting at line 97), Vybrid requires writing a one for clearing > > an interrupt flag. Syncing the method for clearing I2SR_IIF in > > i2c_imx_isr(). > > > > Signed-off-by: Christian Eggers <ceggers@arri.de> > > Cc: stable@vger.kernel.org > > --- > > drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++----- > > 1 file changed, 15 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > > index 0ab5381aa012..745f4071155a 100644 > > --- a/drivers/i2c/busses/i2c-imx.c > > +++ b/drivers/i2c/busses/i2c-imx.c > > @@ -412,6 +412,19 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) > > dma->chan_using = NULL; > > } > > > > +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. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ | [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --] ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-06 12:46 ` Uwe Kleine-König 0 siblings, 0 replies; 34+ messages in thread From: Uwe Kleine-König @ 2020-10-06 12:46 UTC (permalink / raw) To: David Laight Cc: Pengutronix Kernel Team, 'Christian Eggers', Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Fabio Estevam, Shawn Guo, linux-arm-kernel, linux-i2c [-- Attachment #1.1: Type: text/plain, Size: 1949 bytes --] On Tue, Oct 06, 2020 at 12:06:36PM +0000, David Laight wrote: > From: Christian Eggers > > Sent: 06 October 2020 11:52 > > > > According to the "VFxxx Controller Reference Manual" (and the comment > > block starting at line 97), Vybrid requires writing a one for clearing > > an interrupt flag. Syncing the method for clearing I2SR_IIF in > > i2c_imx_isr(). > > > > Signed-off-by: Christian Eggers <ceggers@arri.de> > > Cc: stable@vger.kernel.org > > --- > > drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++----- > > 1 file changed, 15 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > > index 0ab5381aa012..745f4071155a 100644 > > --- a/drivers/i2c/busses/i2c-imx.c > > +++ b/drivers/i2c/busses/i2c-imx.c > > @@ -412,6 +412,19 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) > > dma->chan_using = NULL; > > } > > > > +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. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ | [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --] [-- Attachment #2: Type: text/plain, Size: 176 bytes --] _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* RE: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag 2020-10-06 12:46 ` Uwe Kleine-König @ 2020-10-06 12:52 ` David Laight -1 siblings, 0 replies; 34+ messages in thread From: David Laight @ 2020-10-06 12:52 UTC (permalink / raw) To: 'Uwe Kleine-König' Cc: 'Christian Eggers', Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, linux-arm-kernel, linux-i2c 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) ^ permalink raw reply [flat|nested] 34+ messages in thread
* RE: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag @ 2020-10-06 12:52 ` David Laight 0 siblings, 0 replies; 34+ messages in thread From: David Laight @ 2020-10-06 12:52 UTC (permalink / raw) To: 'Uwe Kleine-König' Cc: Pengutronix Kernel Team, 'Christian Eggers', Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Fabio Estevam, Shawn Guo, linux-arm-kernel, linux-i2c 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 ^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH v3 2/3] i2c: imx: Check for I2SR_IAL after every byte 2020-10-06 10:51 ` Christian Eggers @ 2020-10-06 10:51 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, Christian Eggers, stable Arbitration Lost (IAL) can happen after every single byte transfer. If arbitration is lost, the I2C hardware will autonomously switch from master mode to slave. If a transfer is not aborted in this state, consecutive transfers will not be executed by the hardware and will timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 745f4071155a..bf0e94814222 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -490,6 +490,16 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool atomic) dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__); return -ETIMEDOUT; } + + /* check for arbitration lost */ + if (i2c_imx->i2csr & I2SR_IAL) { + dev_dbg(&i2c_imx->adapter.dev, "<%s> Arbitration lost\n", __func__); + i2c_imx_clear_irq(i2c_imx, I2SR_IAL); + + i2c_imx->i2csr = 0; + return -EAGAIN; + } + dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__); i2c_imx->i2csr = 0; return 0; -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v3 2/3] i2c: imx: Check for I2SR_IAL after every byte @ 2020-10-06 10:51 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, Christian Eggers, linux-arm-kernel, linux-i2c Arbitration Lost (IAL) can happen after every single byte transfer. If arbitration is lost, the I2C hardware will autonomously switch from master mode to slave. If a transfer is not aborted in this state, consecutive transfers will not be executed by the hardware and will timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 745f4071155a..bf0e94814222 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -490,6 +490,16 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool atomic) dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__); return -ETIMEDOUT; } + + /* check for arbitration lost */ + if (i2c_imx->i2csr & I2SR_IAL) { + dev_dbg(&i2c_imx->adapter.dev, "<%s> Arbitration lost\n", __func__); + i2c_imx_clear_irq(i2c_imx, I2SR_IAL); + + i2c_imx->i2csr = 0; + return -EAGAIN; + } + dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__); i2c_imx->i2csr = 0; return 0; -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v3 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost 2020-10-06 10:51 ` Christian Eggers @ 2020-10-06 10:51 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, Christian Eggers, stable If arbitration is lost, the master automatically changes to slave mode. I2SR_IBB may or may not be reset by hardware. Raising a STOP condition by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. So calling i2c_imx_bus_busy() is not required and would busy-wait until timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove # the 3rd argument from the calls to # i2c_imx_bus_busy(). --- drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index bf0e94814222..1619c78a17d7 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -615,6 +615,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx, bool atomic) /* Stop I2C transaction */ dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); if (i2c_imx->dma) temp &= ~I2CR_DMAEN; @@ -778,9 +780,12 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, */ dev_dbg(dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, false); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, false); } else { /* * For i2c master receiver repeat restart operation like: @@ -905,9 +910,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, dev_dbg(&i2c_imx->adapter.dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, atomic); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, atomic); } else { /* * For i2c master receiver repeat restart operation like: -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v3 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost @ 2020-10-06 10:51 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-06 10:51 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, Christian Eggers, linux-arm-kernel, linux-i2c If arbitration is lost, the master automatically changes to slave mode. I2SR_IBB may or may not be reset by hardware. Raising a STOP condition by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. So calling i2c_imx_bus_busy() is not required and would busy-wait until timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove # the 3rd argument from the calls to # i2c_imx_bus_busy(). --- drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index bf0e94814222..1619c78a17d7 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -615,6 +615,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx, bool atomic) /* Stop I2C transaction */ dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); if (i2c_imx->dma) temp &= ~I2CR_DMAEN; @@ -778,9 +780,12 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, */ dev_dbg(dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, false); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, false); } else { /* * For i2c master receiver repeat restart operation like: @@ -905,9 +910,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, dev_dbg(&i2c_imx->adapter.dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, atomic); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, atomic); } else { /* * For i2c master receiver repeat restart operation like: -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte 2020-10-02 15:23 ` Christian Eggers @ 2020-10-02 15:23 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, Christian Eggers, stable Arbitration Lost (IAL) can happen after every single byte transfer. If arbitration is lost, the I2C hardware will autonomously switch from master mode to slave. If a transfer is not aborted in this state, consecutive transfers will not be executed by the hardware and will timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 34648df7f1a6..1db1e2f5296e 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -483,6 +483,24 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool atomic) dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__); return -ETIMEDOUT; } + + /* check for arbitration lost */ + if (i2c_imx->i2csr & I2SR_IAL) { + unsigned int temp; + + dev_dbg(&i2c_imx->adapter.dev, "<%s> Arbitration lost\n", __func__); + /* + * i2sr_clr_opcode is the value to clear all interrupts. + * Here we want to clear only I2SR_IAL, so we write + * ~i2sr_clr_opcode with just the I2SR_IAL bit toggled. + */ + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IAL; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); + + i2c_imx->i2csr = 0; + return -EAGAIN; + } + dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__); i2c_imx->i2csr = 0; return 0; -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte @ 2020-10-02 15:23 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, Christian Eggers, linux-arm-kernel, linux-i2c Arbitration Lost (IAL) can happen after every single byte transfer. If arbitration is lost, the I2C hardware will autonomously switch from master mode to slave. If a transfer is not aborted in this state, consecutive transfers will not be executed by the hardware and will timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 34648df7f1a6..1db1e2f5296e 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -483,6 +483,24 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool atomic) dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__); return -ETIMEDOUT; } + + /* check for arbitration lost */ + if (i2c_imx->i2csr & I2SR_IAL) { + unsigned int temp; + + dev_dbg(&i2c_imx->adapter.dev, "<%s> Arbitration lost\n", __func__); + /* + * i2sr_clr_opcode is the value to clear all interrupts. + * Here we want to clear only I2SR_IAL, so we write + * ~i2sr_clr_opcode with just the I2SR_IAL bit toggled. + */ + temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ I2SR_IAL; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR); + + i2c_imx->i2csr = 0; + return -EAGAIN; + } + dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__); i2c_imx->i2csr = 0; return 0; -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 34+ messages in thread
* Re: [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte 2020-10-02 15:23 ` Christian Eggers @ 2020-10-05 8:07 ` Krzysztof Kozlowski -1 siblings, 0 replies; 34+ messages in thread From: Krzysztof Kozlowski @ 2020-10-05 8:07 UTC (permalink / raw) To: Christian Eggers Cc: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König, Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, stable On Fri, Oct 02, 2020 at 05:23:04PM +0200, Christian Eggers wrote: > Arbitration Lost (IAL) can happen after every single byte transfer. If > arbitration is lost, the I2C hardware will autonomously switch from > master mode to slave. If a transfer is not aborted in this state, > consecutive transfers will not be executed by the hardware and will > timeout. > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@kernel.org> The I2C on Vybrid VF500 still works fine. I did not test this actual condition (arbitration) but only a regular I2C driver (BQ27xxx fuel gauge). Obviously this only proves that regular operation is not broken... Alternatively if you have a specific testing procedure (reproduction of a problem), please share. Best regards, Krzysztof ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte @ 2020-10-05 8:07 ` Krzysztof Kozlowski 0 siblings, 0 replies; 34+ messages in thread From: Krzysztof Kozlowski @ 2020-10-05 8:07 UTC (permalink / raw) To: Christian Eggers Cc: Shawn Guo, Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Pengutronix Kernel Team, Uwe Kleine-König, Fabio Estevam, linux-arm-kernel, linux-i2c On Fri, Oct 02, 2020 at 05:23:04PM +0200, Christian Eggers wrote: > Arbitration Lost (IAL) can happen after every single byte transfer. If > arbitration is lost, the I2C hardware will autonomously switch from > master mode to slave. If a transfer is not aborted in this state, > consecutive transfers will not be executed by the hardware and will > timeout. > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org > --- > drivers/i2c/busses/i2c-imx.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@kernel.org> The I2C on Vybrid VF500 still works fine. I did not test this actual condition (arbitration) but only a regular I2C driver (BQ27xxx fuel gauge). Obviously this only proves that regular operation is not broken... Alternatively if you have a specific testing procedure (reproduction of a problem), please share. Best regards, Krzysztof _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte 2020-10-05 8:07 ` Krzysztof Kozlowski @ 2020-10-05 9:25 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-05 9:25 UTC (permalink / raw) To: Krzysztof Kozlowski Cc: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König, Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, stable On Monday, 5 October 2020, 10:07:25 CEST, Krzysztof Kozlowski wrote: > The I2C on Vybrid VF500 still works fine. I did not test this actual > condition (arbitration) but only a regular I2C driver (BQ27xxx fuel > gauge). Obviously this only proves that regular operation is not > broken... thank you very much for testing on Vybrid. > Alternatively if you have a specific testing procedure (reproduction of > a problem), please share. The IAL errors happen due to noise on our I2C bus. We have our power supply connected via I2C. The hardware designers wanted to make sure that no high currents flow through the ground pins of the I2C interface. So they added a series resistor (30 Ohm) in the GND line between the power supply and the i.MX board. If you have an I2C device on an external PCB, adding some small series resistance in the GND line may cause IAL errors. On the other hand, if everything else works fine, also handling if IAL should work on Vybrid. > Best regards, > Krzysztof Best regards Christian ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte @ 2020-10-05 9:25 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-05 9:25 UTC (permalink / raw) To: Krzysztof Kozlowski Cc: Shawn Guo, Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Pengutronix Kernel Team, Uwe Kleine-König, Fabio Estevam, linux-arm-kernel, linux-i2c On Monday, 5 October 2020, 10:07:25 CEST, Krzysztof Kozlowski wrote: > The I2C on Vybrid VF500 still works fine. I did not test this actual > condition (arbitration) but only a regular I2C driver (BQ27xxx fuel > gauge). Obviously this only proves that regular operation is not > broken... thank you very much for testing on Vybrid. > Alternatively if you have a specific testing procedure (reproduction of > a problem), please share. The IAL errors happen due to noise on our I2C bus. We have our power supply connected via I2C. The hardware designers wanted to make sure that no high currents flow through the ground pins of the I2C interface. So they added a series resistor (30 Ohm) in the GND line between the power supply and the i.MX board. If you have an I2C device on an external PCB, adding some small series resistance in the GND line may cause IAL errors. On the other hand, if everything else works fine, also handling if IAL should work on Vybrid. > Best regards, > Krzysztof Best regards Christian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
* [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost 2020-10-02 15:23 ` Christian Eggers @ 2020-10-02 15:23 ` Christian Eggers -1 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, Christian Eggers, stable If arbitration is lost, the master automatically changes to slave mode. I2SR_IBB may or may not be reset by hardware. Raising a STOP condition by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. So calling i2c_imx_bus_busy() is not required and would busy-wait until timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove # the 3rd argument from the calls to # i2c_imx_bus_busy(). --- drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 1db1e2f5296e..ced9cb3a2665 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -616,6 +616,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx, bool atomic) /* Stop I2C transaction */ dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); if (i2c_imx->dma) temp &= ~I2CR_DMAEN; @@ -785,9 +787,12 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, */ dev_dbg(dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, false); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, false); } else { /* * For i2c master receiver repeat restart operation like: @@ -912,9 +917,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, dev_dbg(&i2c_imx->adapter.dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, atomic); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, atomic); } else { /* * For i2c master receiver repeat restart operation like: -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler ^ permalink raw reply related [flat|nested] 34+ messages in thread
* [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost @ 2020-10-02 15:23 ` Christian Eggers 0 siblings, 0 replies; 34+ messages in thread From: Christian Eggers @ 2020-10-02 15:23 UTC (permalink / raw) To: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König Cc: linux-kernel, stable, NXP Linux Team, Pengutronix Kernel Team, Christian Eggers, linux-arm-kernel, linux-i2c If arbitration is lost, the master automatically changes to slave mode. I2SR_IBB may or may not be reset by hardware. Raising a STOP condition by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. So calling i2c_imx_bus_busy() is not required and would busy-wait until timeout. Signed-off-by: Christian Eggers <ceggers@arri.de> Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove # the 3rd argument from the calls to # i2c_imx_bus_busy(). --- drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 1db1e2f5296e..ced9cb3a2665 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -616,6 +616,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx, bool atomic) /* Stop I2C transaction */ dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); if (i2c_imx->dma) temp &= ~I2CR_DMAEN; @@ -785,9 +787,12 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, */ dev_dbg(dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, false); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, false); } else { /* * For i2c master receiver repeat restart operation like: @@ -912,9 +917,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, dev_dbg(&i2c_imx->adapter.dev, "<%s> clear MSTA\n", __func__); temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + if (!(temp & I2CR_MSTA)) + i2c_imx->stopped = 1; temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); - i2c_imx_bus_busy(i2c_imx, 0, atomic); + if (!i2c_imx->stopped) + i2c_imx_bus_busy(i2c_imx, 0, atomic); } else { /* * For i2c master receiver repeat restart operation like: -- Christian Eggers Embedded software developer Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRA 57918 Persoenlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: Muenchen - Registergericht: Amtsgericht Muenchen - Handelsregisternummer: HRB 54477 Geschaeftsfuehrer: Dr. Michael Neuhaeuser; Stephan Schenk; Walter Trauninger; Markus Zeiler _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 34+ messages in thread
* Re: [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost 2020-10-02 15:23 ` Christian Eggers @ 2020-10-05 8:16 ` Krzysztof Kozlowski -1 siblings, 0 replies; 34+ messages in thread From: Krzysztof Kozlowski @ 2020-10-05 8:16 UTC (permalink / raw) To: Christian Eggers Cc: Oleksij Rempel, Shawn Guo, Sascha Hauer, Fabio Estevam, Uwe Kleine-König, Pengutronix Kernel Team, NXP Linux Team, linux-i2c, linux-arm-kernel, linux-kernel, stable On Fri, Oct 02, 2020 at 05:23:05PM +0200, Christian Eggers wrote: > If arbitration is lost, the master automatically changes to slave mode. > I2SR_IBB may or may not be reset by hardware. Raising a STOP condition > by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. > > So calling i2c_imx_bus_busy() is not required and would busy-wait until > timeout. > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove > # the 3rd argument from the calls to > # i2c_imx_bus_busy(). > --- > drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@kernel.org> The I2C on Vybrid VF500 still works fine (also bigger transfers). I did not test this actual condition (arbitration) but only a regular I2C driver (BQ27xxx fuel gauge). Obviously this only proves that regular operation is not broken... Best regards, Krzysztof ^ permalink raw reply [flat|nested] 34+ messages in thread
* Re: [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost @ 2020-10-05 8:16 ` Krzysztof Kozlowski 0 siblings, 0 replies; 34+ messages in thread From: Krzysztof Kozlowski @ 2020-10-05 8:16 UTC (permalink / raw) To: Christian Eggers Cc: Shawn Guo, Sascha Hauer, linux-kernel, stable, Oleksij Rempel, NXP Linux Team, Pengutronix Kernel Team, Uwe Kleine-König, Fabio Estevam, linux-arm-kernel, linux-i2c On Fri, Oct 02, 2020 at 05:23:05PM +0200, Christian Eggers wrote: > If arbitration is lost, the master automatically changes to slave mode. > I2SR_IBB may or may not be reset by hardware. Raising a STOP condition > by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB. > > So calling i2c_imx_bus_busy() is not required and would busy-wait until > timeout. > > Signed-off-by: Christian Eggers <ceggers@arri.de> > Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove > # the 3rd argument from the calls to > # i2c_imx_bus_busy(). > --- > drivers/i2c/busses/i2c-imx.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@kernel.org> The I2C on Vybrid VF500 still works fine (also bigger transfers). I did not test this actual condition (arbitration) but only a regular I2C driver (BQ27xxx fuel gauge). Obviously this only proves that regular operation is not broken... Best regards, Krzysztof _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 34+ messages in thread
end of thread, other threads:[~2020-10-06 12:53 UTC | newest] Thread overview: 34+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 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 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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