Optimize performance for single irq
Changes since v1. * Add member to hold sdio_single_irq function in mmc_card and minimize new code in process_sdio_pending_irqs * Clarify commit message
Stefan Nilsson XK (1): sdio: optimized SDIO IRQ handling for single irq
drivers/mmc/core/sdio_irq.c | 30 ++++++++++++++++++++++++++++++ include/linux/mmc/card.h | 1 + 2 files changed, 31 insertions(+), 0 deletions(-)
From: Stefan Nilsson XK stefan.xk.nilsson@stericsson.com
If there is only 1 function registered it is possible to improve performance by directly calling the irq handler and avoiding the overhead of reading the CCCR registers.
Signed-off-by: Per Forlin per.forlin@linaro.org Acked-by: Ulf Hansson ulf.hansson@stericsson.com --- drivers/mmc/core/sdio_irq.c | 30 ++++++++++++++++++++++++++++++ include/linux/mmc/card.h | 1 + 2 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c index b300161..64c4409 100644 --- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) int i, ret, count; unsigned char pending;
+ /* + * Optimization, if there is only 1 function registered + * call irq handler directly + */ + if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) { + struct sdio_func *func = card->sdio_single_irq; + func->irq_handler(func); + return 1; + } + ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_INTx, 0, &pending); if (ret) { printk(KERN_DEBUG "%s: error %d reading SDIO_CCCR_INTx\n", @@ -186,6 +196,24 @@ static int sdio_card_irq_put(struct mmc_card *card) return 0; }
+/* If there is only 1 function registered set sdio_single_irq */ +static void sdio_single_irq_set(struct mmc_card *card) +{ + struct sdio_func *func; + int i; + + card->sdio_single_irq = NULL; + if ((card->host->caps & MMC_CAP_SDIO_IRQ) && + card->host->sdio_irqs == 1) + for (i = 0; i < card->sdio_funcs; i++) { + func = card->sdio_func[i]; + if (func && func->irq_handler) { + card->sdio_single_irq = func; + break; + } + } +} + /** * sdio_claim_irq - claim the IRQ for a SDIO function * @func: SDIO function @@ -227,6 +255,7 @@ int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler) ret = sdio_card_irq_get(func->card); if (ret) func->irq_handler = NULL; + sdio_single_irq_set(func->card);
return ret; } @@ -251,6 +280,7 @@ int sdio_release_irq(struct sdio_func *func) if (func->irq_handler) { func->irq_handler = NULL; sdio_card_irq_put(func->card); + sdio_single_irq_set(func->card); }
ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, ®); diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h index adb4888..0d64211 100644 --- a/include/linux/mmc/card.h +++ b/include/linux/mmc/card.h @@ -145,6 +145,7 @@ struct mmc_card { struct sdio_cccr cccr; /* common card info */ struct sdio_cis cis; /* common tuple info */ struct sdio_func *sdio_func[SDIO_MAX_FUNCS]; /* SDIO functions (devices) */ + struct sdio_func *sdio_single_irq; /* SDIO function when only one IRQ active */ unsigned num_info; /* number of info strings */ const char **info; /* info strings */ struct sdio_func_tuple *tuples; /* unknown common tuples */
2011/5/4 Per Forlin per.forlin@linaro.org:
From: Stefan Nilsson XK stefan.xk.nilsson@stericsson.com
If there is only 1 function registered it is possible to improve performance by directly calling the irq handler and avoiding the overhead of reading the CCCR registers.
[...]
--- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) int i, ret, count; unsigned char pending;
- /*
- * Optimization, if there is only 1 function registered
- * call irq handler directly
- */
- if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
- struct sdio_func *func = card->sdio_single_irq;
- func->irq_handler(func);
- return 1;
- }
[...]
The second condition can be avoided:
in process_sdio_pending_irqs():
if (card->sdio_irq_func) call handler and return
in sdio_claim_irq():
card->func->irq_handler = ... if (host->sdio_irqs == 1) card->sdio_irq_func = func; else card->sdio_irq_func = NULL;
in sdio_release_irq():
card->sdio_irq_func = NULL; card->func->irq_handler = ... sdio_card_irq_put(); if (host->sdio_irqs == 1) sdio_single_irq_set(func->card);
in struct mmc_card: struct sdio_func *sdio_irq_func;
Best Regards, Michał Mirosław
2011/5/4 Michał Mirosław mirqus@gmail.com:
2011/5/4 Per Forlin per.forlin@linaro.org:
From: Stefan Nilsson XK stefan.xk.nilsson@stericsson.com
If there is only 1 function registered it is possible to improve performance by directly calling the irq handler and avoiding the overhead of reading the CCCR registers.
[...]
--- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) int i, ret, count; unsigned char pending;
- /*
- * Optimization, if there is only 1 function registered
- * call irq handler directly
- */
- if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
- struct sdio_func *func = card->sdio_single_irq;
- func->irq_handler(func);
- return 1;
- }
[...]
The second condition can be avoided:
in process_sdio_pending_irqs():
if (card->sdio_irq_func) call handler and return
I added the second condition as a sanity check. Same check is used in the main for loop
ret = -EINVAL; } else if (func->irq_handler) { func->irq_handler(func);
Is the second check necessary here?
in sdio_claim_irq():
card->func->irq_handler = ... if (host->sdio_irqs == 1) card->sdio_irq_func = func; else card->sdio_irq_func = NULL;
I wanted to keep it simple and use same function in claim and release. Your code looks nice. Is if safe to not check the condition "(card->host->caps & MMC_CAP_SDIO_IRQ)". What happens if the SDIO is in polling mode?
in sdio_release_irq():
card->sdio_irq_func = NULL; card->func->irq_handler = ... sdio_card_irq_put(); if (host->sdio_irqs == 1) sdio_single_irq_set(func->card);
This works for me.
in struct mmc_card: struct sdio_func *sdio_irq_func;
The name sdio_single_irq indicates it is only used for single irq. "sdio_irq_func" is too generic I think. But the your name is shorter and makes the indentation look nicer. Not a big deal really.
I will wait until tomorrow to post patch v3. This will give time for other to comment as well.
Best Regards, Michał Mirosław
Thanks for your feedback, Per
On Wed, 4 May 2011, Per Forlin wrote:
2011/5/4 Michał Mirosław mirqus@gmail.com:
2011/5/4 Per Forlin per.forlin@linaro.org:
From: Stefan Nilsson XK stefan.xk.nilsson@stericsson.com
If there is only 1 function registered it is possible to improve performance by directly calling the irq handler and avoiding the overhead of reading the CCCR registers.
[...]
--- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) int i, ret, count; unsigned char pending;
- /*
- * Optimization, if there is only 1 function registered
- * call irq handler directly
- */
- if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
- struct sdio_func *func = card->sdio_single_irq;
- func->irq_handler(func);
- return 1;
- }
[...]
The second condition can be avoided:
in process_sdio_pending_irqs():
if (card->sdio_irq_func) call handler and return
I added the second condition as a sanity check. Same check is used in the main for loop
ret = -EINVAL; } else if (func->irq_handler) { func->irq_handler(func);
Is the second check necessary here?
Yes because we want to be notified if the hardware returns pending interrupt flags for interrupts we didn't claim.
in sdio_claim_irq():
card->func->irq_handler = ... if (host->sdio_irqs == 1) card->sdio_irq_func = func; else card->sdio_irq_func = NULL;
I wanted to keep it simple and use same function in claim and release. Your code looks nice. Is if safe to not check the condition "(card->host->caps & MMC_CAP_SDIO_IRQ)". What happens if the SDIO is in polling mode?
You cannot avoid checking MMC_CAP_SDIO_IRQ. If it isn't set the CCCr register must be polled in all cases.
Nicolas
On Wed, 4 May 2011, Per Forlin wrote:
From: Stefan Nilsson XK stefan.xk.nilsson@stericsson.com
If there is only 1 function registered it is possible to improve performance by directly calling the irq handler and avoiding the overhead of reading the CCCR registers.
Signed-off-by: Per Forlin per.forlin@linaro.org Acked-by: Ulf Hansson ulf.hansson@stericsson.com
drivers/mmc/core/sdio_irq.c | 30 ++++++++++++++++++++++++++++++ include/linux/mmc/card.h | 1 + 2 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c index b300161..64c4409 100644 --- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) int i, ret, count; unsigned char pending;
- /*
* Optimization, if there is only 1 function registered* call irq handler directly*/- if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
struct sdio_func *func = card->sdio_single_irq;func->irq_handler(func);
I think there is little point using a func variable here, especially since you already reference the handler pointer in the if() statement. Hence:
if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) { card->sdio_single_irq->irq_handler(); return 1; }
@@ -186,6 +196,24 @@ static int sdio_card_irq_put(struct mmc_card *card) return 0; } +/* If there is only 1 function registered set sdio_single_irq */ +static void sdio_single_irq_set(struct mmc_card *card) +{
The comment is slightly wrong. This should say "only 1 function interrupt registered..." Nothing prevents this from working with multiple functions if only one of them has claimed an interrupt.
Other than that:
Reviewed-by: Nicolas Pitre nicolas.pitre@linaro.org
Nicolas
On 4 May 2011 19:34, Nicolas Pitre nicolas.pitre@linaro.org wrote:
On Wed, 4 May 2011, Per Forlin wrote:
From: Stefan Nilsson XK stefan.xk.nilsson@stericsson.com
If there is only 1 function registered it is possible to improve performance by directly calling the irq handler and avoiding the overhead of reading the CCCR registers.
Signed-off-by: Per Forlin per.forlin@linaro.org Acked-by: Ulf Hansson ulf.hansson@stericsson.com
drivers/mmc/core/sdio_irq.c | 30 ++++++++++++++++++++++++++++++ include/linux/mmc/card.h | 1 + 2 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c index b300161..64c4409 100644 --- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) int i, ret, count; unsigned char pending;
- /*
- * Optimization, if there is only 1 function registered
- * call irq handler directly
- */
- if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
- struct sdio_func *func = card->sdio_single_irq;
- func->irq_handler(func);
I think there is little point using a func variable here, especially since you already reference the handler pointer in the if() statement. Hence:
if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) { card->sdio_single_irq->irq_handler(); return 1; }
What do you think about: + struct sdio_func *func = card->sdio_single_irq; + + /* + * Optimization, if there is only 1 function interrupt registered + * call irq handler directly + */ + if (func) { + func->irq_handler(func); + return 1; + }
- struct sdio_func *func = card->sdio_func[i - 1]; + func = card->sdio_func[i - 1];
@@ -186,6 +196,24 @@ static int sdio_card_irq_put(struct mmc_card *card) return 0; }
+/* If there is only 1 function registered set sdio_single_irq */ +static void sdio_single_irq_set(struct mmc_card *card) +{
The comment is slightly wrong. This should say "only 1 function interrupt registered..." Nothing prevents this from working with multiple functions if only one of them has claimed an interrupt.
Other than that:
Reviewed-by: Nicolas Pitre nicolas.pitre@linaro.org
Nicolas
On Wed, 4 May 2011, Per Forlin wrote:
On 4 May 2011 19:34, Nicolas Pitre nicolas.pitre@linaro.org wrote:
On Wed, 4 May 2011, Per Forlin wrote:
From: Stefan Nilsson XK stefan.xk.nilsson@stericsson.com
If there is only 1 function registered it is possible to improve performance by directly calling the irq handler and avoiding the overhead of reading the CCCR registers.
Signed-off-by: Per Forlin per.forlin@linaro.org Acked-by: Ulf Hansson ulf.hansson@stericsson.com
drivers/mmc/core/sdio_irq.c | 30 ++++++++++++++++++++++++++++++ include/linux/mmc/card.h | 1 + 2 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c index b300161..64c4409 100644 --- a/drivers/mmc/core/sdio_irq.c +++ b/drivers/mmc/core/sdio_irq.c @@ -32,6 +32,16 @@ static int process_sdio_pending_irqs(struct mmc_card *card) int i, ret, count; unsigned char pending;
- /*
- * Optimization, if there is only 1 function registered
- * call irq handler directly
- */
- if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) {
- struct sdio_func *func = card->sdio_single_irq;
- func->irq_handler(func);
I think there is little point using a func variable here, especially since you already reference the handler pointer in the if() statement. Hence:
if (card->sdio_single_irq && card->sdio_single_irq->irq_handler) { card->sdio_single_irq->irq_handler(); return 1; }
What do you think about:
struct sdio_func *func = card->sdio_single_irq;/** Optimization, if there is only 1 function interrupt registered* call irq handler directly*/if (func) {func->irq_handler(func);return 1;}
Sure, but I'd move the assignment right before the if() in that case for clarity:
struct sdio_func *func;
/* * Optimization, if there is only 1 function interrupt registered * call irq handler directly */ func = card->sdio_single_irq; if (func) { func->irq_handler(func); return 1; } [...]
Nicolas
-
Michał Mirosław -
Nicolas Pitre -
Per Forlin