[PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[rentao.bupt]

From: Tao Ren <rentao.bupt@gmail.com>

This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
improve vhub port irq handling"): for_each_set_bit() is replaced with
simple for() loop because for() loop runs faster on ASPEED BMC.

Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
---
 drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
 drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
index cdf96911e4b1..be7bb64e3594 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
@@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
 
 	/* Handle device interrupts */
 	if (istat & vhub->port_irq_mask) {
-		unsigned long bitmap = istat;
-		int offset = VHUB_IRQ_DEV1_BIT;
-		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
-
-		for_each_set_bit_from(offset, &bitmap, size) {
-			i = offset - VHUB_IRQ_DEV1_BIT;
-			ast_vhub_dev_irq(&vhub->ports[i].dev);
+		for (i = 0; i < vhub->max_ports; i++) {
+			if (istat & VHUB_DEV_IRQ(i))
+				ast_vhub_dev_irq(&vhub->ports[i].dev);
 		}
 	}
 
diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
index 2e5a1ef14a75..87a5dea12d3c 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
+++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
@@ -67,6 +67,9 @@
 #define VHUB_IRQ_HUB_EP0_SETUP			(1 << 0)
 #define VHUB_IRQ_ACK_ALL			0x1ff
 
+/* Downstream device IRQ mask. */
+#define VHUB_DEV_IRQ(n)				(VHUB_IRQ_DEVICE1 << (n))
+
 /* SW reset reg */
 #define VHUB_SW_RESET_EP_POOL			(1 << 9)
 #define VHUB_SW_RESET_DMA_CONTROLLER		(1 << 8)
-- 
2.17.1

[PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[rentao.bupt]

From: Tao Ren <rentao.bupt@gmail.com>

This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
improve vhub port irq handling"): for_each_set_bit() is replaced with
simple for() loop because for() loop runs faster on ASPEED BMC.

Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
---
 drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
 drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
index cdf96911e4b1..be7bb64e3594 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
@@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
 
 	/* Handle device interrupts */
 	if (istat & vhub->port_irq_mask) {
-		unsigned long bitmap = istat;
-		int offset = VHUB_IRQ_DEV1_BIT;
-		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
-
-		for_each_set_bit_from(offset, &bitmap, size) {
-			i = offset - VHUB_IRQ_DEV1_BIT;
-			ast_vhub_dev_irq(&vhub->ports[i].dev);
+		for (i = 0; i < vhub->max_ports; i++) {
+			if (istat & VHUB_DEV_IRQ(i))
+				ast_vhub_dev_irq(&vhub->ports[i].dev);
 		}
 	}
 
diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
index 2e5a1ef14a75..87a5dea12d3c 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
+++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
@@ -67,6 +67,9 @@
 #define VHUB_IRQ_HUB_EP0_SETUP			(1 << 0)
 #define VHUB_IRQ_ACK_ALL			0x1ff
 
+/* Downstream device IRQ mask. */
+#define VHUB_DEV_IRQ(n)				(VHUB_IRQ_DEVICE1 << (n))
+
 /* SW reset reg */
 #define VHUB_SW_RESET_EP_POOL			(1 << 9)
 #define VHUB_SW_RESET_DMA_CONTROLLER		(1 << 8)
-- 
2.17.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Tao Ren]

Hi Ben,

I sent out the follow-on patch per Greg's suggestion, and the purpose is
to include the latest version (v4) of the original commit. As v4 was
already Acked-by you, can I add the tag for this patch? Or are you
willing to Ack it again?


Cheers,

Tao

On Wed, May 27, 2020 at 06:11:54PM -0700, rentao.bupt@gmail.com wrote:
> From: Tao Ren <rentao.bupt@gmail.com>
> 
> This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> improve vhub port irq handling"): for_each_set_bit() is replaced with
> simple for() loop because for() loop runs faster on ASPEED BMC.
> 
> Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> ---
>  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>  2 files changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> index cdf96911e4b1..be7bb64e3594 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>  
>  	/* Handle device interrupts */
>  	if (istat & vhub->port_irq_mask) {
> -		unsigned long bitmap = istat;
> -		int offset = VHUB_IRQ_DEV1_BIT;
> -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> -
> -		for_each_set_bit_from(offset, &bitmap, size) {
> -			i = offset - VHUB_IRQ_DEV1_BIT;
> -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> +		for (i = 0; i < vhub->max_ports; i++) {
> +			if (istat & VHUB_DEV_IRQ(i))
> +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>  		}
>  	}
>  
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> index 2e5a1ef14a75..87a5dea12d3c 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> @@ -67,6 +67,9 @@
>  #define VHUB_IRQ_HUB_EP0_SETUP			(1 << 0)
>  #define VHUB_IRQ_ACK_ALL			0x1ff
>  
> +/* Downstream device IRQ mask. */
> +#define VHUB_DEV_IRQ(n)				(VHUB_IRQ_DEVICE1 << (n))
> +
>  /* SW reset reg */
>  #define VHUB_SW_RESET_EP_POOL			(1 << 9)
>  #define VHUB_SW_RESET_DMA_CONTROLLER		(1 << 8)
> -- 
> 2.17.1
> 

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Tao Ren]

Hi Ben,

I sent out the follow-on patch per Greg's suggestion, and the purpose is
to include the latest version (v4) of the original commit. As v4 was
already Acked-by you, can I add the tag for this patch? Or are you
willing to Ack it again?


Cheers,

Tao

On Wed, May 27, 2020 at 06:11:54PM -0700, rentao.bupt@gmail.com wrote:
> From: Tao Ren <rentao.bupt@gmail.com>
> 
> This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> improve vhub port irq handling"): for_each_set_bit() is replaced with
> simple for() loop because for() loop runs faster on ASPEED BMC.
> 
> Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> ---
>  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>  2 files changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> index cdf96911e4b1..be7bb64e3594 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>  
>  	/* Handle device interrupts */
>  	if (istat & vhub->port_irq_mask) {
> -		unsigned long bitmap = istat;
> -		int offset = VHUB_IRQ_DEV1_BIT;
> -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> -
> -		for_each_set_bit_from(offset, &bitmap, size) {
> -			i = offset - VHUB_IRQ_DEV1_BIT;
> -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> +		for (i = 0; i < vhub->max_ports; i++) {
> +			if (istat & VHUB_DEV_IRQ(i))
> +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>  		}
>  	}
>  
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> index 2e5a1ef14a75..87a5dea12d3c 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> @@ -67,6 +67,9 @@
>  #define VHUB_IRQ_HUB_EP0_SETUP			(1 << 0)
>  #define VHUB_IRQ_ACK_ALL			0x1ff
>  
> +/* Downstream device IRQ mask. */
> +#define VHUB_DEV_IRQ(n)				(VHUB_IRQ_DEVICE1 << (n))
> +
>  /* SW reset reg */
>  #define VHUB_SW_RESET_EP_POOL			(1 << 9)
>  #define VHUB_SW_RESET_DMA_CONTROLLER		(1 << 8)
> -- 
> 2.17.1
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 1581 bytes --]


Hi,

rentao.bupt@gmail.com writes:
> From: Tao Ren <rentao.bupt@gmail.com>
>
> This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> improve vhub port irq handling"): for_each_set_bit() is replaced with
> simple for() loop because for() loop runs faster on ASPEED BMC.
>
> Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> ---
>  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>  2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> index cdf96911e4b1..be7bb64e3594 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>  
>  	/* Handle device interrupts */
>  	if (istat & vhub->port_irq_mask) {
> -		unsigned long bitmap = istat;
> -		int offset = VHUB_IRQ_DEV1_BIT;
> -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> -
> -		for_each_set_bit_from(offset, &bitmap, size) {
> -			i = offset - VHUB_IRQ_DEV1_BIT;
> -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> +		for (i = 0; i < vhub->max_ports; i++) {
> +			if (istat & VHUB_DEV_IRQ(i))
> +				ast_vhub_dev_irq(&vhub->ports[i].dev);

how have you measured your statement above? for_each_set_bit() does
exactly what you did. Unless your architecture has an instruction which
helps finds the next set bit (like cls on ARM), which, then, makes it
much faster.

-- 
balbi

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 857 bytes --]

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

[-- Attachment #1.1: Type: text/plain, Size: 1581 bytes --]


Hi,

rentao.bupt@gmail.com writes:
> From: Tao Ren <rentao.bupt@gmail.com>
>
> This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> improve vhub port irq handling"): for_each_set_bit() is replaced with
> simple for() loop because for() loop runs faster on ASPEED BMC.
>
> Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> ---
>  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>  2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> index cdf96911e4b1..be7bb64e3594 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>  
>  	/* Handle device interrupts */
>  	if (istat & vhub->port_irq_mask) {
> -		unsigned long bitmap = istat;
> -		int offset = VHUB_IRQ_DEV1_BIT;
> -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> -
> -		for_each_set_bit_from(offset, &bitmap, size) {
> -			i = offset - VHUB_IRQ_DEV1_BIT;
> -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> +		for (i = 0; i < vhub->max_ports; i++) {
> +			if (istat & VHUB_DEV_IRQ(i))
> +				ast_vhub_dev_irq(&vhub->ports[i].dev);

how have you measured your statement above? for_each_set_bit() does
exactly what you did. Unless your architecture has an instruction which
helps finds the next set bit (like cls on ARM), which, then, makes it
much faster.

-- 
balbi

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 857 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

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Tao Ren]

On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
> 
> Hi,
> 
> rentao.bupt@gmail.com writes:
> > From: Tao Ren <rentao.bupt@gmail.com>
> >
> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> > improve vhub port irq handling"): for_each_set_bit() is replaced with
> > simple for() loop because for() loop runs faster on ASPEED BMC.
> >
> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> > ---
> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
> >  2 files changed, 6 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > index cdf96911e4b1..be7bb64e3594 100644
> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
> >  
> >  	/* Handle device interrupts */
> >  	if (istat & vhub->port_irq_mask) {
> > -		unsigned long bitmap = istat;
> > -		int offset = VHUB_IRQ_DEV1_BIT;
> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> > -
> > -		for_each_set_bit_from(offset, &bitmap, size) {
> > -			i = offset - VHUB_IRQ_DEV1_BIT;
> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> > +		for (i = 0; i < vhub->max_ports; i++) {
> > +			if (istat & VHUB_DEV_IRQ(i))
> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
> 
> how have you measured your statement above? for_each_set_bit() does
> exactly what you did. Unless your architecture has an instruction which
> helps finds the next set bit (like cls on ARM), which, then, makes it
> much faster.

I did some testing and result shows for() loop runs faster than
for_each_set_bit() loop. Please refer to details below (discussion with
Benjamin in the original patch) and kindly let me know your suggestions.

> On Mon, 2020-04-06 at 23:02 -0700, Tao Ren wrote:
> > I ran some testing on my ast2400 and ast2500 BMC and looks like the
> > for() loop runs faster than for_each_set_bit_from() loop in my
> > environment. I'm not sure if something needs to be revised in my test
> > code, but please kindly share your suggestions:
> >
> > I use get_cycles() to calculate execution time of 2 different loops, and
> > ast_vhub_dev_irq() is replaced with barrier() to avoid "noise"; below
> > are the results:
> >
> >   - when downstream port number is 5 and only 1 irq bit is set, it takes
> >     ~30 cycles to finish for_each_set_bit() loop, and 20-25 cycles to
> >     finish the for() loop.
> >
> >   - if downstream port number is 5 and all 5 bits are set, then
> >     for_each_set_bit() loop takes ~50 cycles and for() loop takes ~25
> >     cycles.
> >
> >   - when I increase downsteam port number to 16 and set 1 irq bit, the
> >     for_each_set_bit() loop takes ~30 cycles and for() loop takes 25
> >     cycles. It's a little surprise to me because I thought for() loop
> >     would cost 60+ cycles (3 times of the value when port number is 5).
> >
> >   - if downstream port number is 16 and all irq status bits are set,
> >     then for_each_set_bit() loop takes 60-70 cycles and for() loop takes
> >     30+ cycles.


Cheers,

Tao

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Tao Ren]

On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
> 
> Hi,
> 
> rentao.bupt@gmail.com writes:
> > From: Tao Ren <rentao.bupt@gmail.com>
> >
> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> > improve vhub port irq handling"): for_each_set_bit() is replaced with
> > simple for() loop because for() loop runs faster on ASPEED BMC.
> >
> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> > ---
> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
> >  2 files changed, 6 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > index cdf96911e4b1..be7bb64e3594 100644
> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
> >  
> >  	/* Handle device interrupts */
> >  	if (istat & vhub->port_irq_mask) {
> > -		unsigned long bitmap = istat;
> > -		int offset = VHUB_IRQ_DEV1_BIT;
> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> > -
> > -		for_each_set_bit_from(offset, &bitmap, size) {
> > -			i = offset - VHUB_IRQ_DEV1_BIT;
> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> > +		for (i = 0; i < vhub->max_ports; i++) {
> > +			if (istat & VHUB_DEV_IRQ(i))
> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
> 
> how have you measured your statement above? for_each_set_bit() does
> exactly what you did. Unless your architecture has an instruction which
> helps finds the next set bit (like cls on ARM), which, then, makes it
> much faster.

I did some testing and result shows for() loop runs faster than
for_each_set_bit() loop. Please refer to details below (discussion with
Benjamin in the original patch) and kindly let me know your suggestions.

> On Mon, 2020-04-06 at 23:02 -0700, Tao Ren wrote:
> > I ran some testing on my ast2400 and ast2500 BMC and looks like the
> > for() loop runs faster than for_each_set_bit_from() loop in my
> > environment. I'm not sure if something needs to be revised in my test
> > code, but please kindly share your suggestions:
> >
> > I use get_cycles() to calculate execution time of 2 different loops, and
> > ast_vhub_dev_irq() is replaced with barrier() to avoid "noise"; below
> > are the results:
> >
> >   - when downstream port number is 5 and only 1 irq bit is set, it takes
> >     ~30 cycles to finish for_each_set_bit() loop, and 20-25 cycles to
> >     finish the for() loop.
> >
> >   - if downstream port number is 5 and all 5 bits are set, then
> >     for_each_set_bit() loop takes ~50 cycles and for() loop takes ~25
> >     cycles.
> >
> >   - when I increase downsteam port number to 16 and set 1 irq bit, the
> >     for_each_set_bit() loop takes ~30 cycles and for() loop takes 25
> >     cycles. It's a little surprise to me because I thought for() loop
> >     would cost 60+ cycles (3 times of the value when port number is 5).
> >
> >   - if downstream port number is 16 and all irq status bits are set,
> >     then for_each_set_bit() loop takes 60-70 cycles and for() loop takes
> >     30+ cycles.


Cheers,

Tao

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 2175 bytes --]


Hi,

Tao Ren <rentao.bupt@gmail.com> writes:
> On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> rentao.bupt@gmail.com writes:
>> > From: Tao Ren <rentao.bupt@gmail.com>
>> >
>> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
>> > improve vhub port irq handling"): for_each_set_bit() is replaced with
>> > simple for() loop because for() loop runs faster on ASPEED BMC.
>> >
>> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
>> > ---
>> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>> >  2 files changed, 6 insertions(+), 7 deletions(-)
>> >
>> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > index cdf96911e4b1..be7bb64e3594 100644
>> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>> >  
>> >  	/* Handle device interrupts */
>> >  	if (istat & vhub->port_irq_mask) {
>> > -		unsigned long bitmap = istat;
>> > -		int offset = VHUB_IRQ_DEV1_BIT;
>> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>> > -
>> > -		for_each_set_bit_from(offset, &bitmap, size) {
>> > -			i = offset - VHUB_IRQ_DEV1_BIT;
>> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
>> > +		for (i = 0; i < vhub->max_ports; i++) {
>> > +			if (istat & VHUB_DEV_IRQ(i))
>> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>> 
>> how have you measured your statement above? for_each_set_bit() does
>> exactly what you did. Unless your architecture has an instruction which
>> helps finds the next set bit (like cls on ARM), which, then, makes it
>> much faster.
>
> I did some testing and result shows for() loop runs faster than
> for_each_set_bit() loop. Please refer to details below (discussion with
> Benjamin in the original patch) and kindly let me know your suggestions.

no strong feelings, just surprised that you're already worried about
20~40 cycles of cpu time ;-)

Patch applied for next merge window

-- 
balbi

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 857 bytes --]

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

[-- Attachment #1.1: Type: text/plain, Size: 2175 bytes --]


Hi,

Tao Ren <rentao.bupt@gmail.com> writes:
> On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> rentao.bupt@gmail.com writes:
>> > From: Tao Ren <rentao.bupt@gmail.com>
>> >
>> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
>> > improve vhub port irq handling"): for_each_set_bit() is replaced with
>> > simple for() loop because for() loop runs faster on ASPEED BMC.
>> >
>> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
>> > ---
>> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>> >  2 files changed, 6 insertions(+), 7 deletions(-)
>> >
>> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > index cdf96911e4b1..be7bb64e3594 100644
>> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>> >  
>> >  	/* Handle device interrupts */
>> >  	if (istat & vhub->port_irq_mask) {
>> > -		unsigned long bitmap = istat;
>> > -		int offset = VHUB_IRQ_DEV1_BIT;
>> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>> > -
>> > -		for_each_set_bit_from(offset, &bitmap, size) {
>> > -			i = offset - VHUB_IRQ_DEV1_BIT;
>> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
>> > +		for (i = 0; i < vhub->max_ports; i++) {
>> > +			if (istat & VHUB_DEV_IRQ(i))
>> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>> 
>> how have you measured your statement above? for_each_set_bit() does
>> exactly what you did. Unless your architecture has an instruction which
>> helps finds the next set bit (like cls on ARM), which, then, makes it
>> much faster.
>
> I did some testing and result shows for() loop runs faster than
> for_each_set_bit() loop. Please refer to details below (discussion with
> Benjamin in the original patch) and kindly let me know your suggestions.

no strong feelings, just surprised that you're already worried about
20~40 cycles of cpu time ;-)

Patch applied for next merge window

-- 
balbi

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 857 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

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 2175 bytes --]


Hi,

Tao Ren <rentao.bupt@gmail.com> writes:
> On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> rentao.bupt@gmail.com writes:
>> > From: Tao Ren <rentao.bupt@gmail.com>
>> >
>> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
>> > improve vhub port irq handling"): for_each_set_bit() is replaced with
>> > simple for() loop because for() loop runs faster on ASPEED BMC.
>> >
>> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
>> > ---
>> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>> >  2 files changed, 6 insertions(+), 7 deletions(-)
>> >
>> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > index cdf96911e4b1..be7bb64e3594 100644
>> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>> >  
>> >  	/* Handle device interrupts */
>> >  	if (istat & vhub->port_irq_mask) {
>> > -		unsigned long bitmap = istat;
>> > -		int offset = VHUB_IRQ_DEV1_BIT;
>> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>> > -
>> > -		for_each_set_bit_from(offset, &bitmap, size) {
>> > -			i = offset - VHUB_IRQ_DEV1_BIT;
>> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
>> > +		for (i = 0; i < vhub->max_ports; i++) {
>> > +			if (istat & VHUB_DEV_IRQ(i))
>> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>> 
>> how have you measured your statement above? for_each_set_bit() does
>> exactly what you did. Unless your architecture has an instruction which
>> helps finds the next set bit (like cls on ARM), which, then, makes it
>> much faster.
>
> I did some testing and result shows for() loop runs faster than
> for_each_set_bit() loop. Please refer to details below (discussion with
> Benjamin in the original patch) and kindly let me know your suggestions.

no strong feelings, just surprised that you're already worried about
20~40 cycles of cpu time ;-)

Patch applied for next merge window

-- 
balbi

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 857 bytes --]

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

[-- Attachment #1.1: Type: text/plain, Size: 2175 bytes --]


Hi,

Tao Ren <rentao.bupt@gmail.com> writes:
> On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> rentao.bupt@gmail.com writes:
>> > From: Tao Ren <rentao.bupt@gmail.com>
>> >
>> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
>> > improve vhub port irq handling"): for_each_set_bit() is replaced with
>> > simple for() loop because for() loop runs faster on ASPEED BMC.
>> >
>> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
>> > ---
>> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
>> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
>> >  2 files changed, 6 insertions(+), 7 deletions(-)
>> >
>> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > index cdf96911e4b1..be7bb64e3594 100644
>> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>> >  
>> >  	/* Handle device interrupts */
>> >  	if (istat & vhub->port_irq_mask) {
>> > -		unsigned long bitmap = istat;
>> > -		int offset = VHUB_IRQ_DEV1_BIT;
>> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>> > -
>> > -		for_each_set_bit_from(offset, &bitmap, size) {
>> > -			i = offset - VHUB_IRQ_DEV1_BIT;
>> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
>> > +		for (i = 0; i < vhub->max_ports; i++) {
>> > +			if (istat & VHUB_DEV_IRQ(i))
>> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>> 
>> how have you measured your statement above? for_each_set_bit() does
>> exactly what you did. Unless your architecture has an instruction which
>> helps finds the next set bit (like cls on ARM), which, then, makes it
>> much faster.
>
> I did some testing and result shows for() loop runs faster than
> for_each_set_bit() loop. Please refer to details below (discussion with
> Benjamin in the original patch) and kindly let me know your suggestions.

no strong feelings, just surprised that you're already worried about
20~40 cycles of cpu time ;-)

Patch applied for next merge window

-- 
balbi

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 857 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

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

Hi,

Tao Ren <rentao.bupt@gmail.com> writes:
>> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > index cdf96911e4b1..be7bb64e3594 100644
>> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>> >  
>> >  	/* Handle device interrupts */
>> >  	if (istat & vhub->port_irq_mask) {
>> > -		unsigned long bitmap = istat;
>> > -		int offset = VHUB_IRQ_DEV1_BIT;
>> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>> > -
>> > -		for_each_set_bit_from(offset, &bitmap, size) {
>> > -			i = offset - VHUB_IRQ_DEV1_BIT;
>> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
>> > +		for (i = 0; i < vhub->max_ports; i++) {
>> > +			if (istat & VHUB_DEV_IRQ(i))
>> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>> 
>> how have you measured your statement above? for_each_set_bit() does
>> exactly what you did. Unless your architecture has an instruction which
>> helps finds the next set bit (like cls on ARM), which, then, makes it
>> much faster.
>
> I did some testing and result shows for() loop runs faster than
> for_each_set_bit() loop. Please refer to details below (discussion with
> Benjamin in the original patch) and kindly let me know your
> suggestions.

no strong feelings, just surprised you're already worried about 20~40
cycles of cpu time ;-)

patch queued for next merge window

-- 
balbi

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Felipe Balbi]

Hi,

Tao Ren <rentao.bupt@gmail.com> writes:
>> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > index cdf96911e4b1..be7bb64e3594 100644
>> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
>> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>> >  
>> >  	/* Handle device interrupts */
>> >  	if (istat & vhub->port_irq_mask) {
>> > -		unsigned long bitmap = istat;
>> > -		int offset = VHUB_IRQ_DEV1_BIT;
>> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>> > -
>> > -		for_each_set_bit_from(offset, &bitmap, size) {
>> > -			i = offset - VHUB_IRQ_DEV1_BIT;
>> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
>> > +		for (i = 0; i < vhub->max_ports; i++) {
>> > +			if (istat & VHUB_DEV_IRQ(i))
>> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
>> 
>> how have you measured your statement above? for_each_set_bit() does
>> exactly what you did. Unless your architecture has an instruction which
>> helps finds the next set bit (like cls on ARM), which, then, makes it
>> much faster.
>
> I did some testing and result shows for() loop runs faster than
> for_each_set_bit() loop. Please refer to details below (discussion with
> Benjamin in the original patch) and kindly let me know your
> suggestions.

no strong feelings, just surprised you're already worried about 20~40
cycles of cpu time ;-)

patch queued for next merge window

-- 
balbi

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Tao Ren]

On Mon, Aug 31, 2020 at 12:54:57PM +0300, Felipe Balbi wrote:
> 
> Hi,
> 
> Tao Ren <rentao.bupt@gmail.com> writes:
> > On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
> >> 
> >> Hi,
> >> 
> >> rentao.bupt@gmail.com writes:
> >> > From: Tao Ren <rentao.bupt@gmail.com>
> >> >
> >> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> >> > improve vhub port irq handling"): for_each_set_bit() is replaced with
> >> > simple for() loop because for() loop runs faster on ASPEED BMC.
> >> >
> >> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> >> > ---
> >> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
> >> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
> >> >  2 files changed, 6 insertions(+), 7 deletions(-)
> >> >
> >> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> >> > index cdf96911e4b1..be7bb64e3594 100644
> >> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> >> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> >> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
> >> >  
> >> >  	/* Handle device interrupts */
> >> >  	if (istat & vhub->port_irq_mask) {
> >> > -		unsigned long bitmap = istat;
> >> > -		int offset = VHUB_IRQ_DEV1_BIT;
> >> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> >> > -
> >> > -		for_each_set_bit_from(offset, &bitmap, size) {
> >> > -			i = offset - VHUB_IRQ_DEV1_BIT;
> >> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> >> > +		for (i = 0; i < vhub->max_ports; i++) {
> >> > +			if (istat & VHUB_DEV_IRQ(i))
> >> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
> >> 
> >> how have you measured your statement above? for_each_set_bit() does
> >> exactly what you did. Unless your architecture has an instruction which
> >> helps finds the next set bit (like cls on ARM), which, then, makes it
> >> much faster.
> >
> > I did some testing and result shows for() loop runs faster than
> > for_each_set_bit() loop. Please refer to details below (discussion with
> > Benjamin in the original patch) and kindly let me know your suggestions.
> 
> no strong feelings, just surprised that you're already worried about
> 20~40 cycles of cpu time ;-)
> 
> Patch applied for next merge window

Thanks Felipe. Ben had some concerns about interrupt handling cost on
AST2400 BMC (ARM9), hence we did the comparison and noticed the small
difference :)


Cheers,

Tao

Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling

[Tao Ren]

On Mon, Aug 31, 2020 at 12:54:57PM +0300, Felipe Balbi wrote:
> 
> Hi,
> 
> Tao Ren <rentao.bupt@gmail.com> writes:
> > On Mon, Aug 17, 2020 at 04:49:32PM +0300, Felipe Balbi wrote:
> >> 
> >> Hi,
> >> 
> >> rentao.bupt@gmail.com writes:
> >> > From: Tao Ren <rentao.bupt@gmail.com>
> >> >
> >> > This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed:
> >> > improve vhub port irq handling"): for_each_set_bit() is replaced with
> >> > simple for() loop because for() loop runs faster on ASPEED BMC.
> >> >
> >> > Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
> >> > ---
> >> >  drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++-------
> >> >  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  3 +++
> >> >  2 files changed, 6 insertions(+), 7 deletions(-)
> >> >
> >> > diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> >> > index cdf96911e4b1..be7bb64e3594 100644
> >> > --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> >> > +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> >> > @@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
> >> >  
> >> >  	/* Handle device interrupts */
> >> >  	if (istat & vhub->port_irq_mask) {
> >> > -		unsigned long bitmap = istat;
> >> > -		int offset = VHUB_IRQ_DEV1_BIT;
> >> > -		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
> >> > -
> >> > -		for_each_set_bit_from(offset, &bitmap, size) {
> >> > -			i = offset - VHUB_IRQ_DEV1_BIT;
> >> > -			ast_vhub_dev_irq(&vhub->ports[i].dev);
> >> > +		for (i = 0; i < vhub->max_ports; i++) {
> >> > +			if (istat & VHUB_DEV_IRQ(i))
> >> > +				ast_vhub_dev_irq(&vhub->ports[i].dev);
> >> 
> >> how have you measured your statement above? for_each_set_bit() does
> >> exactly what you did. Unless your architecture has an instruction which
> >> helps finds the next set bit (like cls on ARM), which, then, makes it
> >> much faster.
> >
> > I did some testing and result shows for() loop runs faster than
> > for_each_set_bit() loop. Please refer to details below (discussion with
> > Benjamin in the original patch) and kindly let me know your suggestions.
> 
> no strong feelings, just surprised that you're already worried about
> 20~40 cycles of cpu time ;-)
> 
> Patch applied for next merge window

Thanks Felipe. Ben had some concerns about interrupt handling cost on
AST2400 BMC (ARM9), hence we did the comparison and noticed the small
difference :)


Cheers,

Tao

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel