[PATCH] bus: mhi: pci_generic: Increase num of elements in hw event ring

[PATCH] bus: mhi: pci_generic: Increase num of elements in hw event ring

[Loic Poulain]

We met some sporadic modem crashes during high throughput testing, this
has been root caused to a lack of elements in the event ring. Indeed,
the modem is simply crashing when event ring becomes empty.

It appears that the total number event ring elements is too low given
the performances of the modem (IPA hardware accelerator). This change
increases the number of elements in the hardware event ring to 2048,
which is aligned with what is defined in downstream version:
https://source.codeaurora.org/quic/la/kernel/msm-4.14/tree/arch/arm64/boot/dts/qcom/sm8150-mhi.dtsi?h=msm-4.14#n482

With this change, modem coes not crash anymore.

Note: An event ring element is 16-Byte, so the total memory usage of
a hardware event ring is now 32KB.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
---
 drivers/bus/mhi/pci_generic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
index 5b3a23a4..c20f59e 100644
--- a/drivers/bus/mhi/pci_generic.c
+++ b/drivers/bus/mhi/pci_generic.c
@@ -129,7 +129,7 @@ struct mhi_pci_dev_info {
 
 #define MHI_EVENT_CONFIG_HW_DATA(ev_ring, ch_num) \
 	{					\
-		.num_elements = 256,		\
+		.num_elements = 2048,		\
 		.irq_moderation_ms = 1,		\
 		.irq = (ev_ring) + 1,		\
 		.priority = 1,			\
-- 
2.7.4

Re: [PATCH] bus: mhi: pci_generic: Increase num of elements in hw event ring

[Manivannan Sadhasivam]

On Fri, Feb 05, 2021 at 09:36:35AM +0100, Loic Poulain wrote:
> We met some sporadic modem crashes during high throughput testing, this
> has been root caused to a lack of elements in the event ring. Indeed,
> the modem is simply crashing when event ring becomes empty.
> 
> It appears that the total number event ring elements is too low given
> the performances of the modem (IPA hardware accelerator). This change
> increases the number of elements in the hardware event ring to 2048,
> which is aligned with what is defined in downstream version:
> https://source.codeaurora.org/quic/la/kernel/msm-4.14/tree/arch/arm64/boot/dts/qcom/sm8150-mhi.dtsi?h=msm-4.14#n482
> 
> With this change, modem coes not crash anymore.
> 
> Note: An event ring element is 16-Byte, so the total memory usage of
> a hardware event ring is now 32KB.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
>  drivers/bus/mhi/pci_generic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
> index 5b3a23a4..c20f59e 100644
> --- a/drivers/bus/mhi/pci_generic.c
> +++ b/drivers/bus/mhi/pci_generic.c
> @@ -129,7 +129,7 @@ struct mhi_pci_dev_info {
>  
>  #define MHI_EVENT_CONFIG_HW_DATA(ev_ring, ch_num) \
>  	{					\
> -		.num_elements = 256,		\
> +		.num_elements = 2048,		\
>  		.irq_moderation_ms = 1,		\
>  		.irq = (ev_ring) + 1,		\
>  		.priority = 1,			\
> -- 
> 2.7.4
> 

Re: [PATCH] bus: mhi: pci_generic: Increase num of elements in hw event ring

[Manivannan Sadhasivam]

On Fri, Feb 05, 2021 at 09:36:35AM +0100, Loic Poulain wrote:
> We met some sporadic modem crashes during high throughput testing, this
> has been root caused to a lack of elements in the event ring. Indeed,
> the modem is simply crashing when event ring becomes empty.
> 
> It appears that the total number event ring elements is too low given
> the performances of the modem (IPA hardware accelerator). This change
> increases the number of elements in the hardware event ring to 2048,
> which is aligned with what is defined in downstream version:
> https://source.codeaurora.org/quic/la/kernel/msm-4.14/tree/arch/arm64/boot/dts/qcom/sm8150-mhi.dtsi?h=msm-4.14#n482
> 
> With this change, modem coes not crash anymore.
> 
> Note: An event ring element is 16-Byte, so the total memory usage of
> a hardware event ring is now 32KB.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

Applied to mhi-next!

Thanks,
Mani

> ---
>  drivers/bus/mhi/pci_generic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
> index 5b3a23a4..c20f59e 100644
> --- a/drivers/bus/mhi/pci_generic.c
> +++ b/drivers/bus/mhi/pci_generic.c
> @@ -129,7 +129,7 @@ struct mhi_pci_dev_info {
>  
>  #define MHI_EVENT_CONFIG_HW_DATA(ev_ring, ch_num) \
>  	{					\
> -		.num_elements = 256,		\
> +		.num_elements = 2048,		\
>  		.irq_moderation_ms = 1,		\
>  		.irq = (ev_ring) + 1,		\
>  		.priority = 1,			\
> -- 
> 2.7.4
> 

Re: [PATCH] bus: mhi: pci_generic: Increase num of elements in hw event ring

[Jeffrey Hugo]

On 2/5/2021 5:34 AM, Manivannan Sadhasivam wrote:
> On Fri, Feb 05, 2021 at 09:36:35AM +0100, Loic Poulain wrote:
>> We met some sporadic modem crashes during high throughput testing, this
>> has been root caused to a lack of elements in the event ring. Indeed,
>> the modem is simply crashing when event ring becomes empty.
>>
>> It appears that the total number event ring elements is too low given
>> the performances of the modem (IPA hardware accelerator). This change
>> increases the number of elements in the hardware event ring to 2048,
>> which is aligned with what is defined in downstream version:
>> https://source.codeaurora.org/quic/la/kernel/msm-4.14/tree/arch/arm64/boot/dts/qcom/sm8150-mhi.dtsi?h=msm-4.14#n482
>>
>> With this change, modem coes not crash anymore.
>>
>> Note: An event ring element is 16-Byte, so the total memory usage of
>> a hardware event ring is now 32KB.
>>
>> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> 
> Applied to mhi-next!
> 
> Thanks,
> Mani


Probably too late, but there is a typo in the commit text.  "modem coes 
not crash" should be "modem does not crash".

-- 
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

Re: [PATCH] bus: mhi: pci_generic: Increase num of elements in hw event ring

[patchwork-bot+linux-arm-msm]

Hello:

This patch was applied to qcom/linux.git (refs/heads/for-next):

On Fri,  5 Feb 2021 09:36:35 +0100 you wrote:
> We met some sporadic modem crashes during high throughput testing, this
> has been root caused to a lack of elements in the event ring. Indeed,
> the modem is simply crashing when event ring becomes empty.
> 
> It appears that the total number event ring elements is too low given
> the performances of the modem (IPA hardware accelerator). This change
> increases the number of elements in the hardware event ring to 2048,
> which is aligned with what is defined in downstream version:
> https://source.codeaurora.org/quic/la/kernel/msm-4.14/tree/arch/arm64/boot/dts/qcom/sm8150-mhi.dtsi?h=msm-4.14#n482
> 
> [...]

Here is the summary with links:
  - bus: mhi: pci_generic: Increase num of elements in hw event ring
    https://git.kernel.org/qcom/c/026c5b1ec29c

You are awesome, thank you!
--
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