[PATCH v4] i2c: imx-lpi2c: directly return ISR when detect a NACK

[PATCH v4] i2c: imx-lpi2c: directly return ISR when detect a NACK

[carlos.song]

From: Carlos Song <carlos.song@nxp.com>

A NACK flag in ISR means i2c bus error. In such condition,
there is no need to do read/write operation.

In this patch, i2c will check MSR_NDF, MSR_RDF and MSR_TDF
flag in turn, it's making mutually exclusive NACK/read/write.
So when a NACK is received(MSR_NDF), i2c will return ISR
directly and then stop i2c transfer.

Signed-off-by: Carlos Song <carlos.song@nxp.com>
---
 drivers/i2c/busses/i2c-imx-lpi2c.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
index 150d923ca7f1..9a3e3a1bc4ee 100644
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -517,14 +517,12 @@ static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
 	temp = readl(lpi2c_imx->base + LPI2C_MSR);
 	temp &= enabled;
 
-	if (temp & MSR_RDF)
-		lpi2c_imx_read_rxfifo(lpi2c_imx);
-
-	if (temp & MSR_TDF)
-		lpi2c_imx_write_txfifo(lpi2c_imx);
-
 	if (temp & MSR_NDF)
 		complete(&lpi2c_imx->complete);
+	else if (temp & MSR_RDF)
+		lpi2c_imx_read_rxfifo(lpi2c_imx);
+	else if (temp & MSR_TDF)
+		lpi2c_imx_write_txfifo(lpi2c_imx);
 
 	return IRQ_HANDLED;
 }
-- 
2.34.1


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Re: [PATCH v4] i2c: imx-lpi2c: directly return ISR when detect a NACK

[Andi Shyti]

Hi Carlos,

On Thu, Jul 27, 2023 at 11:03:47AM +0800, carlos.song@nxp.com wrote:
> From: Carlos Song <carlos.song@nxp.com>
> 
> A NACK flag in ISR means i2c bus error. In such condition,
> there is no need to do read/write operation.
> 
> In this patch, i2c will check MSR_NDF, MSR_RDF and MSR_TDF
> flag in turn, it's making mutually exclusive NACK/read/write.
> So when a NACK is received(MSR_NDF), i2c will return ISR
> directly and then stop i2c transfer.
> 
> Signed-off-by: Carlos Song <carlos.song@nxp.com>

thanks!

Reviewed-by: Andi Shyti <andi.shyti@kernel.org> 

Andi

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Re: [PATCH v4] i2c: imx-lpi2c: directly return ISR when detect a NACK

[Andi Shyti]

Hi

On Thu, 27 Jul 2023 11:03:47 +0800, carlos.song@nxp.com wrote:
> A NACK flag in ISR means i2c bus error. In such condition,
> there is no need to do read/write operation.
> 
> In this patch, i2c will check MSR_NDF, MSR_RDF and MSR_TDF
> flag in turn, it's making mutually exclusive NACK/read/write.
> So when a NACK is received(MSR_NDF), i2c will return ISR
> directly and then stop i2c transfer.
> 
> [...]

Applied to i2c/andi-for-next on

https://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux.git

Please note that this patch may still undergo further evaluation
and the final decision will be made in collaboration with
Wolfram.

Thank you,
Andi

Patches applied
===============
[1/1] i2c: imx-lpi2c: directly return ISR when detect a NACK
      commit: 7525bcc34ec49a39e8b56f5911431a5a2a981896

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Re: [PATCH v4] i2c: imx-lpi2c: directly return ISR when detect a NACK

[Wolfram Sang]

[-- Attachment #1.1: Type: text/plain, Size: 600 bytes --]

On Wed, Aug 02, 2023 at 10:10:31PM +0200, Andi Shyti wrote:
> Hi
> 
> On Thu, 27 Jul 2023 11:03:47 +0800, carlos.song@nxp.com wrote:
> > A NACK flag in ISR means i2c bus error. In such condition,
> > there is no need to do read/write operation.
> > 
> > In this patch, i2c will check MSR_NDF, MSR_RDF and MSR_TDF
> > flag in turn, it's making mutually exclusive NACK/read/write.
> > So when a NACK is received(MSR_NDF), i2c will return ISR
> > directly and then stop i2c transfer.
> > 
> > [...]
> 
> Applied to i2c/andi-for-next on

Applied to for-next (via Andi's tree), thanks!


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