diff mbox

[02/28] crypto: omap-sham: Don't idle/start SHA device between Encrypt operations

Message ID 1464771389-10640-3-git-send-email-t-kristo@ti.com (mailing list archive)
State New, archived
Headers show

Commit Message

Tero Kristo June 1, 2016, 8:56 a.m. UTC
From: Lokesh Vutla <lokeshvutla@ti.com>

Calling runtime PM API for every block causes serious perf hit to
crypto operations that are done on a long buffer.
As crypto is performed on a page boundary, encrypting large buffers can
cause a series of crypto operations divided by page. The runtime PM API
is also called those many times.

We call runtime_pm_get_sync only at beginning on the session (cra_init)
and runtime_pm_put at the end. This result in upto a 50% speedup.
This doesn't make the driver to keep the system awake as runtime get/put
is only called during a crypto session which completes usually quickly.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
---
 drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

Comments

Grygorii Strashko June 1, 2016, 9:53 a.m. UTC | #1
On 06/01/2016 11:56 AM, Tero Kristo wrote:
> From: Lokesh Vutla <lokeshvutla@ti.com>
>
> Calling runtime PM API for every block causes serious perf hit to
> crypto operations that are done on a long buffer.
> As crypto is performed on a page boundary, encrypting large buffers can
> cause a series of crypto operations divided by page. The runtime PM API
> is also called those many times.
>
> We call runtime_pm_get_sync only at beginning on the session (cra_init)
> and runtime_pm_put at the end. This result in upto a 50% speedup.
> This doesn't make the driver to keep the system awake as runtime get/put
> is only called during a crypto session which completes usually quickly.
>
> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
> Signed-off-by: Tero Kristo <t-kristo@ti.com>
> ---
>   drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
>   1 file changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
> index 6eefaa2..bd0258f 100644
> --- a/drivers/crypto/omap-sham.c
> +++ b/drivers/crypto/omap-sham.c
> @@ -360,14 +360,6 @@ static void omap_sham_copy_ready_hash(struct ahash_request *req)
>
>   static int omap_sham_hw_init(struct omap_sham_dev *dd)
>   {
> -	int err;
> -
> -	err = pm_runtime_get_sync(dd->dev);
> -	if (err < 0) {
> -		dev_err(dd->dev, "failed to get sync: %d\n", err);
> -		return err;
> -	}
> -
>   	if (!test_bit(FLAGS_INIT, &dd->flags)) {
>   		set_bit(FLAGS_INIT, &dd->flags);
>   		dd->err = 0;
> @@ -999,8 +991,6 @@ static void omap_sham_finish_req(struct ahash_request *req, int err)
>   	dd->flags &= ~(BIT(FLAGS_BUSY) | BIT(FLAGS_FINAL) | BIT(FLAGS_CPU) |
>   			BIT(FLAGS_DMA_READY) | BIT(FLAGS_OUTPUT_READY));
>
> -	pm_runtime_put(dd->dev);
> -
>   	if (req->base.complete)
>   		req->base.complete(&req->base, err);
>
> @@ -1239,6 +1229,7 @@ static int omap_sham_cra_init_alg(struct crypto_tfm *tfm, const char *alg_base)
>   {
>   	struct omap_sham_ctx *tctx = crypto_tfm_ctx(tfm);
>   	const char *alg_name = crypto_tfm_alg_name(tfm);
> +	struct omap_sham_dev *dd;
>
>   	/* Allocate a fallback and abort if it failed. */
>   	tctx->fallback = crypto_alloc_shash(alg_name, 0,
> @@ -1266,6 +1257,13 @@ static int omap_sham_cra_init_alg(struct crypto_tfm *tfm, const char *alg_base)
>
>   	}
>
> +	spin_lock_bh(&sham.lock);
> +	list_for_each_entry(dd, &sham.dev_list, list) {
> +		break;
> +	}
> +	spin_unlock_bh(&sham.lock);
> +
> +	pm_runtime_get_sync(dd->dev);
>   	return 0;
>   }
>
> @@ -1307,6 +1305,7 @@ static int omap_sham_cra_sha512_init(struct crypto_tfm *tfm)
>   static void omap_sham_cra_exit(struct crypto_tfm *tfm)
>   {
>   	struct omap_sham_ctx *tctx = crypto_tfm_ctx(tfm);
> +	struct omap_sham_dev *dd;
>
>   	crypto_free_shash(tctx->fallback);
>   	tctx->fallback = NULL;
> @@ -1315,6 +1314,14 @@ static void omap_sham_cra_exit(struct crypto_tfm *tfm)
>   		struct omap_sham_hmac_ctx *bctx = tctx->base;
>   		crypto_free_shash(bctx->shash);
>   	}
> +
> +	spin_lock_bh(&sham.lock);
> +	list_for_each_entry(dd, &sham.dev_list, list) {
> +		break;
> +	}
> +	spin_unlock_bh(&sham.lock);
> +
> +	pm_runtime_get_sync(dd->dev);

May be put_?

>   }
>
>   static struct ahash_alg algs_sha1_md5[] = {
>
Dave Gerlach June 1, 2016, 11:03 p.m. UTC | #2
On 06/01/2016 04:53 AM, Grygorii Strashko wrote:
> On 06/01/2016 11:56 AM, Tero Kristo wrote:
>> From: Lokesh Vutla <lokeshvutla@ti.com>
>>
>> Calling runtime PM API for every block causes serious perf hit to
>> crypto operations that are done on a long buffer.
>> As crypto is performed on a page boundary, encrypting large buffers can
>> cause a series of crypto operations divided by page. The runtime PM API
>> is also called those many times.
>>
>> We call runtime_pm_get_sync only at beginning on the session (cra_init)
>> and runtime_pm_put at the end. This result in upto a 50% speedup.
>> This doesn't make the driver to keep the system awake as runtime get/put
>> is only called during a crypto session which completes usually quickly.
>>
>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>> ---
>>   drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
>>   1 file changed, 17 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
>> index 6eefaa2..bd0258f 100644
>> --- a/drivers/crypto/omap-sham.c
>> +++ b/drivers/crypto/omap-sham.c
>> @@ -360,14 +360,6 @@ static void omap_sham_copy_ready_hash(struct
>> ahash_request *req)
>>
>>   static int omap_sham_hw_init(struct omap_sham_dev *dd)
>>   {
>> -    int err;
>> -
>> -    err = pm_runtime_get_sync(dd->dev);
>> -    if (err < 0) {
>> -        dev_err(dd->dev, "failed to get sync: %d\n", err);
>> -        return err;
>> -    }
>> -

Would it be worth it to investigate a pm_runtime autosuspend approach 
rather than knocking runtime PM out here completely? I am not clear if 
the overhead is coming from the pm_runtime calls themselves or the 
actual idling of the IP, but if it's the idling of the IP causing the 
slowdown, with a large enough autosuspend_delay we don't actually sleep 
between each block but after a long enough period of idle time we would 
actually suspend.

Regards,
Dave

>>       if (!test_bit(FLAGS_INIT, &dd->flags)) {
>>           set_bit(FLAGS_INIT, &dd->flags);
>>           dd->err = 0;
>> @@ -999,8 +991,6 @@ static void omap_sham_finish_req(struct
>> ahash_request *req, int err)
>>       dd->flags &= ~(BIT(FLAGS_BUSY) | BIT(FLAGS_FINAL) |
>> BIT(FLAGS_CPU) |
>>               BIT(FLAGS_DMA_READY) | BIT(FLAGS_OUTPUT_READY));
>>
>> -    pm_runtime_put(dd->dev);
>> -
>>       if (req->base.complete)
>>           req->base.complete(&req->base, err);
>>
>> @@ -1239,6 +1229,7 @@ static int omap_sham_cra_init_alg(struct
>> crypto_tfm *tfm, const char *alg_base)
>>   {
>>       struct omap_sham_ctx *tctx = crypto_tfm_ctx(tfm);
>>       const char *alg_name = crypto_tfm_alg_name(tfm);
>> +    struct omap_sham_dev *dd;
>>
>>       /* Allocate a fallback and abort if it failed. */
>>       tctx->fallback = crypto_alloc_shash(alg_name, 0,
>> @@ -1266,6 +1257,13 @@ static int omap_sham_cra_init_alg(struct
>> crypto_tfm *tfm, const char *alg_base)
>>
>>       }
>>
>> +    spin_lock_bh(&sham.lock);
>> +    list_for_each_entry(dd, &sham.dev_list, list) {
>> +        break;
>> +    }
>> +    spin_unlock_bh(&sham.lock);
>> +
>> +    pm_runtime_get_sync(dd->dev);
>>       return 0;
>>   }
>>
>> @@ -1307,6 +1305,7 @@ static int omap_sham_cra_sha512_init(struct
>> crypto_tfm *tfm)
>>   static void omap_sham_cra_exit(struct crypto_tfm *tfm)
>>   {
>>       struct omap_sham_ctx *tctx = crypto_tfm_ctx(tfm);
>> +    struct omap_sham_dev *dd;
>>
>>       crypto_free_shash(tctx->fallback);
>>       tctx->fallback = NULL;
>> @@ -1315,6 +1314,14 @@ static void omap_sham_cra_exit(struct
>> crypto_tfm *tfm)
>>           struct omap_sham_hmac_ctx *bctx = tctx->base;
>>           crypto_free_shash(bctx->shash);
>>       }
>> +
>> +    spin_lock_bh(&sham.lock);
>> +    list_for_each_entry(dd, &sham.dev_list, list) {
>> +        break;
>> +    }
>> +    spin_unlock_bh(&sham.lock);
>> +
>> +    pm_runtime_get_sync(dd->dev);
>
> May be put_?
>
>>   }
>>
>>   static struct ahash_alg algs_sha1_md5[] = {
>>
>
>

--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Herbert Xu June 7, 2016, 10:08 a.m. UTC | #3
On Wed, Jun 01, 2016 at 06:03:52PM -0500, Dave Gerlach wrote:
> On 06/01/2016 04:53 AM, Grygorii Strashko wrote:
> >On 06/01/2016 11:56 AM, Tero Kristo wrote:
> >>From: Lokesh Vutla <lokeshvutla@ti.com>
> >>
> >>Calling runtime PM API for every block causes serious perf hit to
> >>crypto operations that are done on a long buffer.
> >>As crypto is performed on a page boundary, encrypting large buffers can
> >>cause a series of crypto operations divided by page. The runtime PM API
> >>is also called those many times.
> >>
> >>We call runtime_pm_get_sync only at beginning on the session (cra_init)
> >>and runtime_pm_put at the end. This result in upto a 50% speedup.
> >>This doesn't make the driver to keep the system awake as runtime get/put
> >>is only called during a crypto session which completes usually quickly.
> >>
> >>Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
> >>Signed-off-by: Tero Kristo <t-kristo@ti.com>
> >>---
> >>  drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
> >>  1 file changed, 17 insertions(+), 10 deletions(-)
> >>
> >>diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
> >>index 6eefaa2..bd0258f 100644
> >>--- a/drivers/crypto/omap-sham.c
> >>+++ b/drivers/crypto/omap-sham.c
> >>@@ -360,14 +360,6 @@ static void omap_sham_copy_ready_hash(struct
> >>ahash_request *req)
> >>
> >>  static int omap_sham_hw_init(struct omap_sham_dev *dd)
> >>  {
> >>-    int err;
> >>-
> >>-    err = pm_runtime_get_sync(dd->dev);
> >>-    if (err < 0) {
> >>-        dev_err(dd->dev, "failed to get sync: %d\n", err);
> >>-        return err;
> >>-    }
> >>-
> 
> Would it be worth it to investigate a pm_runtime autosuspend
> approach rather than knocking runtime PM out here completely? I am
> not clear if the overhead is coming from the pm_runtime calls
> themselves or the actual idling of the IP, but if it's the idling of
> the IP causing the slowdown, with a large enough autosuspend_delay
> we don't actually sleep between each block but after a long enough
> period of idle time we would actually suspend.

Indeed, I think this patch is bogus.  cra_init is associated
with the tfm object which is usually long-lived.  So doing power
management there makes no sense.

Cheers,
Tero Kristo June 7, 2016, 11:52 a.m. UTC | #4
On 07/06/16 13:08, Herbert Xu wrote:
> On Wed, Jun 01, 2016 at 06:03:52PM -0500, Dave Gerlach wrote:
>> On 06/01/2016 04:53 AM, Grygorii Strashko wrote:
>>> On 06/01/2016 11:56 AM, Tero Kristo wrote:
>>>> From: Lokesh Vutla <lokeshvutla@ti.com>
>>>>
>>>> Calling runtime PM API for every block causes serious perf hit to
>>>> crypto operations that are done on a long buffer.
>>>> As crypto is performed on a page boundary, encrypting large buffers can
>>>> cause a series of crypto operations divided by page. The runtime PM API
>>>> is also called those many times.
>>>>
>>>> We call runtime_pm_get_sync only at beginning on the session (cra_init)
>>>> and runtime_pm_put at the end. This result in upto a 50% speedup.
>>>> This doesn't make the driver to keep the system awake as runtime get/put
>>>> is only called during a crypto session which completes usually quickly.
>>>>
>>>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
>>>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>>>> ---
>>>>   drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
>>>>   1 file changed, 17 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
>>>> index 6eefaa2..bd0258f 100644
>>>> --- a/drivers/crypto/omap-sham.c
>>>> +++ b/drivers/crypto/omap-sham.c
>>>> @@ -360,14 +360,6 @@ static void omap_sham_copy_ready_hash(struct
>>>> ahash_request *req)
>>>>
>>>>   static int omap_sham_hw_init(struct omap_sham_dev *dd)
>>>>   {
>>>> -    int err;
>>>> -
>>>> -    err = pm_runtime_get_sync(dd->dev);
>>>> -    if (err < 0) {
>>>> -        dev_err(dd->dev, "failed to get sync: %d\n", err);
>>>> -        return err;
>>>> -    }
>>>> -
>>
>> Would it be worth it to investigate a pm_runtime autosuspend
>> approach rather than knocking runtime PM out here completely? I am
>> not clear if the overhead is coming from the pm_runtime calls
>> themselves or the actual idling of the IP, but if it's the idling of
>> the IP causing the slowdown, with a large enough autosuspend_delay
>> we don't actually sleep between each block but after a long enough
>> period of idle time we would actually suspend.
>
> Indeed, I think this patch is bogus.  cra_init is associated
> with the tfm object which is usually long-lived.  So doing power
> management there makes no sense.
>
> Cheers,
>

I can investigate this further, but I believe this patch itself gave a 
noticeable performance boost.

This is an optimization anyway, and not critical for functionality.

-Tero
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Grygorii Strashko June 7, 2016, 12:24 p.m. UTC | #5
On 06/07/2016 02:52 PM, Tero Kristo wrote:
> On 07/06/16 13:08, Herbert Xu wrote:
>> On Wed, Jun 01, 2016 at 06:03:52PM -0500, Dave Gerlach wrote:
>>> On 06/01/2016 04:53 AM, Grygorii Strashko wrote:
>>>> On 06/01/2016 11:56 AM, Tero Kristo wrote:
>>>>> From: Lokesh Vutla <lokeshvutla@ti.com>
>>>>>
>>>>> Calling runtime PM API for every block causes serious perf hit to
>>>>> crypto operations that are done on a long buffer.
>>>>> As crypto is performed on a page boundary, encrypting large buffers
>>>>> can
>>>>> cause a series of crypto operations divided by page. The runtime PM
>>>>> API
>>>>> is also called those many times.
>>>>>
>>>>> We call runtime_pm_get_sync only at beginning on the session
>>>>> (cra_init)
>>>>> and runtime_pm_put at the end. This result in upto a 50% speedup.
>>>>> This doesn't make the driver to keep the system awake as runtime
>>>>> get/put
>>>>> is only called during a crypto session which completes usually
>>>>> quickly.
>>>>>
>>>>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
>>>>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>>>>> ---
>>>>>   drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
>>>>>   1 file changed, 17 insertions(+), 10 deletions(-)
>>>>>
>>>>> diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
>>>>> index 6eefaa2..bd0258f 100644
>>>>> --- a/drivers/crypto/omap-sham.c
>>>>> +++ b/drivers/crypto/omap-sham.c
>>>>> @@ -360,14 +360,6 @@ static void omap_sham_copy_ready_hash(struct
>>>>> ahash_request *req)
>>>>>
>>>>>   static int omap_sham_hw_init(struct omap_sham_dev *dd)
>>>>>   {
>>>>> -    int err;
>>>>> -
>>>>> -    err = pm_runtime_get_sync(dd->dev);
>>>>> -    if (err < 0) {
>>>>> -        dev_err(dd->dev, "failed to get sync: %d\n", err);
>>>>> -        return err;
>>>>> -    }
>>>>> -
>>>
>>> Would it be worth it to investigate a pm_runtime autosuspend
>>> approach rather than knocking runtime PM out here completely? I am
>>> not clear if the overhead is coming from the pm_runtime calls
>>> themselves or the actual idling of the IP, but if it's the idling of
>>> the IP causing the slowdown, with a large enough autosuspend_delay
>>> we don't actually sleep between each block but after a long enough
>>> period of idle time we would actually suspend.
>>
>> Indeed, I think this patch is bogus.  cra_init is associated
>> with the tfm object which is usually long-lived.  So doing power
>> management there makes no sense.
>>
>> Cheers,
>>
>
> I can investigate this further, but I believe this patch itself gave a
> noticeable performance boost.
>
> This is an optimization anyway, and not critical for functionality.
>

It is not critical only if below code would not introduce races
+	spin_lock_bh(&sham.lock);
+	list_for_each_entry(dd, &sham.dev_list, list) {
+		break;
+	}
+	spin_unlock_bh(&sham.lock);

Is it guaranteed that dd will alive always at this moment?

+
+	pm_runtime_get_sync(dd->dev);
Tero Kristo June 22, 2016, 9:17 a.m. UTC | #6
On 07/06/16 15:24, Grygorii Strashko wrote:
> On 06/07/2016 02:52 PM, Tero Kristo wrote:
>> On 07/06/16 13:08, Herbert Xu wrote:
>>> On Wed, Jun 01, 2016 at 06:03:52PM -0500, Dave Gerlach wrote:
>>>> On 06/01/2016 04:53 AM, Grygorii Strashko wrote:
>>>>> On 06/01/2016 11:56 AM, Tero Kristo wrote:
>>>>>> From: Lokesh Vutla <lokeshvutla@ti.com>
>>>>>>
>>>>>> Calling runtime PM API for every block causes serious perf hit to
>>>>>> crypto operations that are done on a long buffer.
>>>>>> As crypto is performed on a page boundary, encrypting large buffers
>>>>>> can
>>>>>> cause a series of crypto operations divided by page. The runtime PM
>>>>>> API
>>>>>> is also called those many times.
>>>>>>
>>>>>> We call runtime_pm_get_sync only at beginning on the session
>>>>>> (cra_init)
>>>>>> and runtime_pm_put at the end. This result in upto a 50% speedup.
>>>>>> This doesn't make the driver to keep the system awake as runtime
>>>>>> get/put
>>>>>> is only called during a crypto session which completes usually
>>>>>> quickly.
>>>>>>
>>>>>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
>>>>>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>>>>>> ---
>>>>>>   drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
>>>>>>   1 file changed, 17 insertions(+), 10 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
>>>>>> index 6eefaa2..bd0258f 100644
>>>>>> --- a/drivers/crypto/omap-sham.c
>>>>>> +++ b/drivers/crypto/omap-sham.c
>>>>>> @@ -360,14 +360,6 @@ static void omap_sham_copy_ready_hash(struct
>>>>>> ahash_request *req)
>>>>>>
>>>>>>   static int omap_sham_hw_init(struct omap_sham_dev *dd)
>>>>>>   {
>>>>>> -    int err;
>>>>>> -
>>>>>> -    err = pm_runtime_get_sync(dd->dev);
>>>>>> -    if (err < 0) {
>>>>>> -        dev_err(dd->dev, "failed to get sync: %d\n", err);
>>>>>> -        return err;
>>>>>> -    }
>>>>>> -
>>>>
>>>> Would it be worth it to investigate a pm_runtime autosuspend
>>>> approach rather than knocking runtime PM out here completely? I am
>>>> not clear if the overhead is coming from the pm_runtime calls
>>>> themselves or the actual idling of the IP, but if it's the idling of
>>>> the IP causing the slowdown, with a large enough autosuspend_delay
>>>> we don't actually sleep between each block but after a long enough
>>>> period of idle time we would actually suspend.
>>>
>>> Indeed, I think this patch is bogus.  cra_init is associated
>>> with the tfm object which is usually long-lived.  So doing power
>>> management there makes no sense.
>>>
>>> Cheers,
>>>
>>
>> I can investigate this further, but I believe this patch itself gave a
>> noticeable performance boost.
>>
>> This is an optimization anyway, and not critical for functionality.
>>
>
> It is not critical only if below code would not introduce races

I don't get your point here. This patch is an optimization, and the 
driver works fine without it.

> +    spin_lock_bh(&sham.lock);
> +    list_for_each_entry(dd, &sham.dev_list, list) {
> +        break;
> +    }
> +    spin_unlock_bh(&sham.lock);
>
> Is it guaranteed that dd will alive always at this moment?

Typically yes, but I think there might be a race condition here if the 
driver is removed during operation. Anyway, I'll drop this patch and 
change the optimization to use autosuspend as Dave suggested; that gives 
almost the same performance boost as this one (I miss a couple of 
percent in the overall performance, but I can live with that.)

-Tero

>
> +
> +    pm_runtime_get_sync(dd->dev);
>
>
>


--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
diff mbox

Patch

diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
index 6eefaa2..bd0258f 100644
--- a/drivers/crypto/omap-sham.c
+++ b/drivers/crypto/omap-sham.c
@@ -360,14 +360,6 @@  static void omap_sham_copy_ready_hash(struct ahash_request *req)
 
 static int omap_sham_hw_init(struct omap_sham_dev *dd)
 {
-	int err;
-
-	err = pm_runtime_get_sync(dd->dev);
-	if (err < 0) {
-		dev_err(dd->dev, "failed to get sync: %d\n", err);
-		return err;
-	}
-
 	if (!test_bit(FLAGS_INIT, &dd->flags)) {
 		set_bit(FLAGS_INIT, &dd->flags);
 		dd->err = 0;
@@ -999,8 +991,6 @@  static void omap_sham_finish_req(struct ahash_request *req, int err)
 	dd->flags &= ~(BIT(FLAGS_BUSY) | BIT(FLAGS_FINAL) | BIT(FLAGS_CPU) |
 			BIT(FLAGS_DMA_READY) | BIT(FLAGS_OUTPUT_READY));
 
-	pm_runtime_put(dd->dev);
-
 	if (req->base.complete)
 		req->base.complete(&req->base, err);
 
@@ -1239,6 +1229,7 @@  static int omap_sham_cra_init_alg(struct crypto_tfm *tfm, const char *alg_base)
 {
 	struct omap_sham_ctx *tctx = crypto_tfm_ctx(tfm);
 	const char *alg_name = crypto_tfm_alg_name(tfm);
+	struct omap_sham_dev *dd;
 
 	/* Allocate a fallback and abort if it failed. */
 	tctx->fallback = crypto_alloc_shash(alg_name, 0,
@@ -1266,6 +1257,13 @@  static int omap_sham_cra_init_alg(struct crypto_tfm *tfm, const char *alg_base)
 
 	}
 
+	spin_lock_bh(&sham.lock);
+	list_for_each_entry(dd, &sham.dev_list, list) {
+		break;
+	}
+	spin_unlock_bh(&sham.lock);
+
+	pm_runtime_get_sync(dd->dev);
 	return 0;
 }
 
@@ -1307,6 +1305,7 @@  static int omap_sham_cra_sha512_init(struct crypto_tfm *tfm)
 static void omap_sham_cra_exit(struct crypto_tfm *tfm)
 {
 	struct omap_sham_ctx *tctx = crypto_tfm_ctx(tfm);
+	struct omap_sham_dev *dd;
 
 	crypto_free_shash(tctx->fallback);
 	tctx->fallback = NULL;
@@ -1315,6 +1314,14 @@  static void omap_sham_cra_exit(struct crypto_tfm *tfm)
 		struct omap_sham_hmac_ctx *bctx = tctx->base;
 		crypto_free_shash(bctx->shash);
 	}
+
+	spin_lock_bh(&sham.lock);
+	list_for_each_entry(dd, &sham.dev_list, list) {
+		break;
+	}
+	spin_unlock_bh(&sham.lock);
+
+	pm_runtime_get_sync(dd->dev);
 }
 
 static struct ahash_alg algs_sha1_md5[] = {