diff mbox series

[01/10] spi: dw: Add support for polled operation via no IRQ specified in DT

Message ID 20200513140031.25633-2-lars.povlsen@microchip.com (mailing list archive)
State Superseded
Headers show
Series spi: Adding support for Microchip Sparx5 SoC | expand

Commit Message

Lars Povlsen May 13, 2020, 2 p.m. UTC 
With this change a SPI controller can be added without having a IRQ
associated, and causing all transfers to be polled. For SPI controllers
without DMA, this can significantly improve performance by less
interrupt handling overhead.

Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
---
 drivers/spi/spi-dw.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

--
2.26.2

Comments

Mark Brown May 13, 2020, 2:20 p.m. UTC | #1 
On Wed, May 13, 2020 at 04:00:22PM +0200, Lars Povlsen wrote:
> With this change a SPI controller can be added without having a IRQ
> associated, and causing all transfers to be polled. For SPI controllers
> without DMA, this can significantly improve performance by less
> interrupt handling overhead.

This overlaps substantially with some work that Serge Semin (CCed) has
in progress, please coordinate with him.
Mark Brown May 13, 2020, 2:37 p.m. UTC | #2 
On Wed, May 13, 2020 at 04:00:22PM +0200, Lars Povlsen wrote:

> +#define VALID_IRQ(i) (i >= 0)
> +

This isn't something that should be defined by an individual driver, it
should be in a generic header.
Andy Shevchenko May 13, 2020, 2:55 p.m. UTC | #3 
On Wed, May 13, 2020 at 5:03 PM Lars Povlsen <lars.povlsen@microchip.com> wrote:
>
> With this change a SPI controller can be added without having a IRQ
> associated, and causing all transfers to be polled. For SPI controllers
> without DMA, this can significantly improve performance by less
> interrupt handling overhead.

...

> +#define VALID_IRQ(i) (i >= 0)

drivers/rtc/rtc-cmos.c:95:#define is_valid_irq(n)               ((n) > 0)

Candidate to be in include/linux/irq.h ?

...

> +       if (VALID_IRQ(dws->irq))
> +               free_irq(dws->irq, master);

Isn't free_irq() aware of invalid ones (not found IRQ in the tree or
any other backend container won't do anything)?


>  err_free_master:
>         spi_controller_put(master);
>         return ret;
> --
> 2.26.2



--
With Best Regards,
Andy Shevchenko
Serge Semin May 14, 2020, 1:04 p.m. UTC | #4 
Hi Mark

On Wed, May 13, 2020 at 03:20:50PM +0100, Mark Brown wrote:
> On Wed, May 13, 2020 at 04:00:22PM +0200, Lars Povlsen wrote:
> > With this change a SPI controller can be added without having a IRQ
> > associated, and causing all transfers to be polled. For SPI controllers
> > without DMA, this can significantly improve performance by less
> > interrupt handling overhead.
> 
> This overlaps substantially with some work that Serge Semin (CCed) has
> in progress, please coordinate with him.

Thanks for copying me these mails. I haven't been Cc'ed in the series and
hasn't been subscribed to the SPI mailing list, so I would have definitely
missed that.

I would like to coordinate my efforts with Lars. I'll have the patchset reviewed
soon in addition providing my comments/suggestions of how to make it useful for
both mine and Lars solution.

One thing I can tell about the mem_ops he implemented, is that they aren't
mem_ops, but dirmap (as you remember it's also implemented in my code, but with
alignment specific), and the exec_mem_op partly consists of a code, which belong
to the supports_op() callback. The rest of my comments will be inlined in the
patches.

-Sergey
Lars Povlsen May 15, 2020, 9:11 a.m. UTC | #5 
Serge Semin writes:

> Hi Mark
>
> On Wed, May 13, 2020 at 03:20:50PM +0100, Mark Brown wrote:
>> On Wed, May 13, 2020 at 04:00:22PM +0200, Lars Povlsen wrote:
>> > With this change a SPI controller can be added without having a IRQ
>> > associated, and causing all transfers to be polled. For SPI controllers
>> > without DMA, this can significantly improve performance by less
>> > interrupt handling overhead.
>>
>> This overlaps substantially with some work that Serge Semin (CCed) has
>> in progress, please coordinate with him.
>
> Thanks for copying me these mails. I haven't been Cc'ed in the series and
> hasn't been subscribed to the SPI mailing list, so I would have definitely
> missed that.
>
> I would like to coordinate my efforts with Lars. I'll have the patchset reviewed
> soon in addition providing my comments/suggestions of how to make it useful for
> both mine and Lars solution.

Serge - thanks for taking on this.

Note that my primary concern now is to get Sparx5 upstreamed. The
mem_ops (or dirmap) and polled mode are both performance enhancements,
which can be pulled from my series if it creates too much noise. I can
then add the necessary on top of your work/current kernel at a later
time.

> One thing I can tell about the mem_ops he implemented, is that they aren't
> mem_ops, but dirmap (as you remember it's also implemented in my code, but with
> alignment specific), and the exec_mem_op partly consists of a code, which belong
> to the supports_op() callback. The rest of my comments will be inlined in the
> patches.
>
> -Sergey
Lars Povlsen May 19, 2020, 10:21 a.m. UTC | #6 
On 13/05/20 15:37, Mark Brown wrote:
> Date: Wed, 13 May 2020 15:37:53 +0100
> From: Mark Brown <broonie@kernel.org>
> To: Lars Povlsen <lars.povlsen@microchip.com>
> Cc: SoC Team <soc@kernel.org>, Microchip Linux Driver Support
>  <UNGLinuxDriver@microchip.com>, linux-spi@vger.kernel.org,
>  devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
>  linux-arm-kernel@lists.infradead.org, Alexandre Belloni
>  <alexandre.belloni@bootlin.com>
> Subject: Re: [PATCH 01/10] spi: dw: Add support for polled operation via no
>  IRQ specified in DT
> User-Agent: Mutt/1.10.1 (2018-07-13)
> 
> On Wed, May 13, 2020 at 04:00:22PM +0200, Lars Povlsen wrote:
> 
> > +#define VALID_IRQ(i) (i >= 0)
> > +
> 
> This isn't something that should be defined by an individual driver, it
> should be in a generic header.

Thanks, I will work with Serge on getting this integrated right.

---Lars
Lars Povlsen May 19, 2020, 10:25 a.m. UTC | #7 
Andy Shevchenko writes:

> On Wed, May 13, 2020 at 5:03 PM Lars Povlsen <lars.povlsen@microchip.com> wrote:
>>
>> With this change a SPI controller can be added without having a IRQ
>> associated, and causing all transfers to be polled. For SPI controllers
>> without DMA, this can significantly improve performance by less
>> interrupt handling overhead.
>
> ...
>
>> +#define VALID_IRQ(i) (i >= 0)
>
> drivers/rtc/rtc-cmos.c:95:#define is_valid_irq(n)               ((n) > 0)
>
> Candidate to be in include/linux/irq.h ?
>
> ...
>
>> +       if (VALID_IRQ(dws->irq))
>> +               free_irq(dws->irq, master);
>
> Isn't free_irq() aware of invalid ones (not found IRQ in the tree or
> any other backend container won't do anything)?
>
>
>>  err_free_master:
>>         spi_controller_put(master);
>>         return ret;
>> --
>> 2.26.2

I'll rework this with Serge.

Thank you!
Serge Semin June 2, 2020, 7:10 p.m. UTC | #8 
On Wed, May 13, 2020 at 04:00:22PM +0200, Lars Povlsen wrote:
> With this change a SPI controller can be added without having a IRQ
> associated, and causing all transfers to be polled. For SPI controllers
> without DMA, this can significantly improve performance by less
> interrupt handling overhead.
> 
> Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
> ---
>  drivers/spi/spi-dw.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index 31e3f866d11a7..e572eb34a3c1a 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -19,6 +19,8 @@
>  #include <linux/debugfs.h>
>  #endif
> 

> +#define VALID_IRQ(i) (i >= 0)

Mark and Andy are right. It is a good candidate to be in a generic IRQ-related
code as Anyd suggested:

> > drivers/rtc/rtc-cmos.c:95:#define is_valid_irq(n)               ((n) > 0)
> > Candidate to be in include/linux/irq.h ?

So if you feel like to author additional useful patch integrated into the
kernel, this one is a good chance for it.

> +
>  /* Slave spi_dev related */
>  struct chip_data {
>  	u8 tmode;		/* TR/TO/RO/EEPROM */
> @@ -359,7 +361,7 @@ static int dw_spi_transfer_one(struct spi_controller *master,
>  			spi_enable_chip(dws, 1);
>  			return ret;
>  		}
> -	} else if (!chip->poll_mode) {
> +	} else if (!chip->poll_mode && VALID_IRQ(dws->irq)) {
>  		txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
>  		dw_writel(dws, DW_SPI_TXFLTR, txlevel);
> 
> @@ -379,7 +381,7 @@ static int dw_spi_transfer_one(struct spi_controller *master,
>  			return ret;
>  	}
> 
> -	if (chip->poll_mode)
> +	if (chip->poll_mode || !VALID_IRQ(dws->irq))
>  		return poll_transfer(dws);

Please note. The chip->poll and the poll_transfer() methods've been discarded
from the driver, since commit 1ceb09717e98 ("spi: dw: remove cs_control and
poll_mode members from chip_data"). So you gonna have to get the
poll_transfer-like method back.

-Sergey

> 
>  	return 1;
> @@ -487,11 +489,13 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
> 
>  	spi_controller_set_devdata(master, dws);
> 
> -	ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
> -			  master);
> -	if (ret < 0) {
> -		dev_err(dev, "can not get IRQ\n");
> -		goto err_free_master;
> +	if (VALID_IRQ(dws->irq)) {
> +		ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED,
> +				  dev_name(dev), master);
> +		if (ret < 0) {
> +			dev_err(dev, "can not get IRQ\n");
> +			goto err_free_master;
> +		}
>  	}
> 
>  	master->use_gpio_descriptors = true;
> @@ -539,7 +543,8 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
>  	if (dws->dma_ops && dws->dma_ops->dma_exit)
>  		dws->dma_ops->dma_exit(dws);
>  	spi_enable_chip(dws, 0);
> -	free_irq(dws->irq, master);
> +	if (VALID_IRQ(dws->irq))
> +		free_irq(dws->irq, master);
>  err_free_master:
>  	spi_controller_put(master);
>  	return ret;
> --
> 2.26.2
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Lars Povlsen June 9, 2020, 9:13 a.m. UTC | #9 
Serge Semin writes:

> On Wed, May 13, 2020 at 04:00:22PM +0200, Lars Povlsen wrote:
>> With this change a SPI controller can be added without having a IRQ
>> associated, and causing all transfers to be polled. For SPI controllers
>> without DMA, this can significantly improve performance by less
>> interrupt handling overhead.
>>
>> Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
>> Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
>> ---
>>  drivers/spi/spi-dw.c | 21 +++++++++++++--------
>>  1 file changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
>> index 31e3f866d11a7..e572eb34a3c1a 100644
>> --- a/drivers/spi/spi-dw.c
>> +++ b/drivers/spi/spi-dw.c
>> @@ -19,6 +19,8 @@
>>  #include <linux/debugfs.h>
>>  #endif
>>
>
>> +#define VALID_IRQ(i) (i >= 0)
>
> Mark and Andy are right. It is a good candidate to be in a generic IRQ-related
> code as Anyd suggested:
>
>> > drivers/rtc/rtc-cmos.c:95:#define is_valid_irq(n)               ((n) > 0)
>> > Candidate to be in include/linux/irq.h ?
>
> So if you feel like to author additional useful patch integrated into the
> kernel, this one is a good chance for it.
>

Yeah, but with the poll_transfer() gone below, I think I'll settle on
just getting this into the current framework. Optimization (as this is)
has less priority. I'll put this on the back burner.

>> +
>>  /* Slave spi_dev related */
>>  struct chip_data {
>>       u8 tmode;               /* TR/TO/RO/EEPROM */
>> @@ -359,7 +361,7 @@ static int dw_spi_transfer_one(struct spi_controller *master,
>>                       spi_enable_chip(dws, 1);
>>                       return ret;
>>               }
>> -     } else if (!chip->poll_mode) {
>> +     } else if (!chip->poll_mode && VALID_IRQ(dws->irq)) {
>>               txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
>>               dw_writel(dws, DW_SPI_TXFLTR, txlevel);
>>
>> @@ -379,7 +381,7 @@ static int dw_spi_transfer_one(struct spi_controller *master,
>>                       return ret;
>>       }
>>
>> -     if (chip->poll_mode)
>> +     if (chip->poll_mode || !VALID_IRQ(dws->irq))
>>               return poll_transfer(dws);
>
> Please note. The chip->poll and the poll_transfer() methods've been discarded
> from the driver, since commit 1ceb09717e98 ("spi: dw: remove cs_control and
> poll_mode members from chip_data"). So you gonna have to get the
> poll_transfer-like method back.
>
> -Sergey
>
>>
>>       return 1;
>> @@ -487,11 +489,13 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
>>
>>       spi_controller_set_devdata(master, dws);
>>
>> -     ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
>> -                       master);
>> -     if (ret < 0) {
>> -             dev_err(dev, "can not get IRQ\n");
>> -             goto err_free_master;
>> +     if (VALID_IRQ(dws->irq)) {
>> +             ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED,
>> +                               dev_name(dev), master);
>> +             if (ret < 0) {
>> +                     dev_err(dev, "can not get IRQ\n");
>> +                     goto err_free_master;
>> +             }
>>       }
>>
>>       master->use_gpio_descriptors = true;
>> @@ -539,7 +543,8 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
>>       if (dws->dma_ops && dws->dma_ops->dma_exit)
>>               dws->dma_ops->dma_exit(dws);
>>       spi_enable_chip(dws, 0);
>> -     free_irq(dws->irq, master);
>> +     if (VALID_IRQ(dws->irq))
>> +             free_irq(dws->irq, master);
>>  err_free_master:
>>       spi_controller_put(master);
>>       return ret;
>> --
>> 2.26.2
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff mbox series

Patch

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 31e3f866d11a7..e572eb34a3c1a 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -19,6 +19,8 @@ 
 #include <linux/debugfs.h>
 #endif

+#define VALID_IRQ(i) (i >= 0)
+
 /* Slave spi_dev related */
 struct chip_data {
 	u8 tmode;		/* TR/TO/RO/EEPROM */
@@ -359,7 +361,7 @@  static int dw_spi_transfer_one(struct spi_controller *master,
 			spi_enable_chip(dws, 1);
 			return ret;
 		}
-	} else if (!chip->poll_mode) {
+	} else if (!chip->poll_mode && VALID_IRQ(dws->irq)) {
 		txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
 		dw_writel(dws, DW_SPI_TXFLTR, txlevel);

@@ -379,7 +381,7 @@  static int dw_spi_transfer_one(struct spi_controller *master,
 			return ret;
 	}

-	if (chip->poll_mode)
+	if (chip->poll_mode || !VALID_IRQ(dws->irq))
 		return poll_transfer(dws);

 	return 1;
@@ -487,11 +489,13 @@  int dw_spi_add_host(struct device *dev, struct dw_spi *dws)

 	spi_controller_set_devdata(master, dws);

-	ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dev_name(dev),
-			  master);
-	if (ret < 0) {
-		dev_err(dev, "can not get IRQ\n");
-		goto err_free_master;
+	if (VALID_IRQ(dws->irq)) {
+		ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED,
+				  dev_name(dev), master);
+		if (ret < 0) {
+			dev_err(dev, "can not get IRQ\n");
+			goto err_free_master;
+		}
 	}

 	master->use_gpio_descriptors = true;
@@ -539,7 +543,8 @@  int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 	if (dws->dma_ops && dws->dma_ops->dma_exit)
 		dws->dma_ops->dma_exit(dws);
 	spi_enable_chip(dws, 0);
-	free_irq(dws->irq, master);
+	if (VALID_IRQ(dws->irq))
+		free_irq(dws->irq, master);
 err_free_master:
 	spi_controller_put(master);
 	return ret;