* [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management
@ 2020-05-14 8:24 Etienne Carriere
2020-05-14 14:29 ` Sudeep Holla
0 siblings, 1 reply; 5+ messages in thread
From: Etienne Carriere @ 2020-05-14 8:24 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-arm-kernel, sudeep.holla, etienne.carriere
Fix management of argument a0 output value of arm_smccc_1_1_invoke() that
should consider only SMCCC_RET_NOT_SUPPORTED as reporting an unsupported
function ID as correctly stated in the inline comment.
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
---
drivers/firmware/arm_scmi/smc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
index 49bc4b0e8428..637ad439545f 100644
--- a/drivers/firmware/arm_scmi/smc.c
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -115,7 +115,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
mutex_unlock(&scmi_info->shmem_lock);
/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
- if (res.a0)
+ if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
return -EOPNOTSUPP;
return 0;
}
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management
2020-05-14 8:24 [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management Etienne Carriere
@ 2020-05-14 14:29 ` Sudeep Holla
2020-05-14 15:06 ` Etienne Carriere
0 siblings, 1 reply; 5+ messages in thread
From: Sudeep Holla @ 2020-05-14 14:29 UTC (permalink / raw)
To: Etienne Carriere; +Cc: linux-kernel, linux-arm-kernel, Sudeep Holla
On Thu, May 14, 2020 at 10:24:28AM +0200, Etienne Carriere wrote:
> Fix management of argument a0 output value of arm_smccc_1_1_invoke() that
> should consider only SMCCC_RET_NOT_SUPPORTED as reporting an unsupported
> function ID as correctly stated in the inline comment.
>
I agree on the comment part, but ...
> Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
> ---
> drivers/firmware/arm_scmi/smc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
> index 49bc4b0e8428..637ad439545f 100644
> --- a/drivers/firmware/arm_scmi/smc.c
> +++ b/drivers/firmware/arm_scmi/smc.c
> @@ -115,7 +115,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
> mutex_unlock(&scmi_info->shmem_lock);
>
> /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
> - if (res.a0)
> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
> return -EOPNOTSUPP;
Now this will return 0 for all values other than SMCCC_RET_NOT_SUPPORTED.
Is that what we need ? Or do you see non-zero res.a0 for a success case ?
If later, we need some fixing, otherwise it is safer to leave it as is
IMO.
--
Regards,
Sudeep
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management
2020-05-14 14:29 ` Sudeep Holla
@ 2020-05-14 15:06 ` Etienne Carriere
2020-05-15 9:34 ` Sudeep Holla
0 siblings, 1 reply; 5+ messages in thread
From: Etienne Carriere @ 2020-05-14 15:06 UTC (permalink / raw)
To: Sudeep Holla
Cc: linux-kernel, moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE
On Thu, 14 May 2020 at 16:29, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Thu, May 14, 2020 at 10:24:28AM +0200, Etienne Carriere wrote:
> > Fix management of argument a0 output value of arm_smccc_1_1_invoke() that
> > should consider only SMCCC_RET_NOT_SUPPORTED as reporting an unsupported
> > function ID as correctly stated in the inline comment.
> >
>
> I agree on the comment part, but ...
>
> > Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
> > ---
> > drivers/firmware/arm_scmi/smc.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
> > index 49bc4b0e8428..637ad439545f 100644
> > --- a/drivers/firmware/arm_scmi/smc.c
> > +++ b/drivers/firmware/arm_scmi/smc.c
> > @@ -115,7 +115,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
> > mutex_unlock(&scmi_info->shmem_lock);
> >
> > /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
> > - if (res.a0)
> > + if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
> > return -EOPNOTSUPP;
>
> Now this will return 0 for all values other than SMCCC_RET_NOT_SUPPORTED.
> Is that what we need ? Or do you see non-zero res.a0 for a success case ?
> If later, we need some fixing, otherwise it is safer to leave it as is
> IMO.
Firmware following SMCCC v1.x for some OEM/SiP invocation may simply
not modify invocation register argument a0 on invocation with a
SCMI-SMC transport function ID.
Resulting in res.a0 == scmi_info->func_id here. Which is, by SMCCC
v1.x not an error.
From SMCCC v1.x only SMCCC_RET_NOT_SUPPORTED (-1 signed extended is a
reserved ) is a generic return error whatever function ID value.
Or consider part of the SCMI-SMC transport API that output arg a0
shall be 0 on success,
SMCCC_RET_NOT_SUPPORTED if function ID is not supported
and any non-zero value for non-generic **error** codes.
etienne
>
> --
> Regards,
> Sudeep
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management
2020-05-14 15:06 ` Etienne Carriere
@ 2020-05-15 9:34 ` Sudeep Holla
2020-05-15 9:57 ` Etienne Carriere
0 siblings, 1 reply; 5+ messages in thread
From: Sudeep Holla @ 2020-05-15 9:34 UTC (permalink / raw)
To: Etienne Carriere; +Cc: linux-kernel, Sudeep Holla, linux-arm-kernel
On Thu, May 14, 2020 at 05:06:22PM +0200, Etienne Carriere wrote:
> On Thu, 14 May 2020 at 16:29, Sudeep Holla <sudeep.holla@arm.com> wrote:
> >
> > On Thu, May 14, 2020 at 10:24:28AM +0200, Etienne Carriere wrote:
> > > Fix management of argument a0 output value of arm_smccc_1_1_invoke() that
> > > should consider only SMCCC_RET_NOT_SUPPORTED as reporting an unsupported
> > > function ID as correctly stated in the inline comment.
> > >
> >
> > I agree on the comment part, but ...
> >
> > > Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
> > > ---
> > > drivers/firmware/arm_scmi/smc.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
> > > index 49bc4b0e8428..637ad439545f 100644
> > > --- a/drivers/firmware/arm_scmi/smc.c
> > > +++ b/drivers/firmware/arm_scmi/smc.c
> > > @@ -115,7 +115,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
> > > mutex_unlock(&scmi_info->shmem_lock);
> > >
> > > /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
> > > - if (res.a0)
> > > + if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
> > > return -EOPNOTSUPP;
> >
> > Now this will return 0 for all values other than SMCCC_RET_NOT_SUPPORTED.
> > Is that what we need ? Or do you see non-zero res.a0 for a success case ?
> > If later, we need some fixing, otherwise it is safer to leave it as is
> > IMO.
>
> Firmware following SMCCC v1.x for some OEM/SiP invocation may simply
> not modify invocation register argument a0 on invocation with a
> SCMI-SMC transport function ID.
Yikes, I need to check specification again for this. I will also
check with the firmware implementation team/
> Resulting in res.a0 == scmi_info->func_id here. Which is, by SMCCC
> v1.x not an error.
>
But that may get fatal the result in some other cases, not here for sure.
But I would rather flag that as error so that it is fixed. Anyways I will
check on this again/
> From SMCCC v1.x only SMCCC_RET_NOT_SUPPORTED (-1 signed extended is a
> reserved ) is a generic return error whatever function ID value.
>
Not really, there are couple more I think now. But yes I need to check
on the generic return part.
> Or consider part of the SCMI-SMC transport API that output arg a0
> shall be 0 on success, SMCCC_RET_NOT_SUPPORTED if function ID is not
> supported and any non-zero value for non-generic **error** codes.
>
I prefer that. Anyways I will check and if anything changes I will ping
back on this thread.
--
Regards,
Sudeep
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management
2020-05-15 9:34 ` Sudeep Holla
@ 2020-05-15 9:57 ` Etienne Carriere
0 siblings, 0 replies; 5+ messages in thread
From: Etienne Carriere @ 2020-05-15 9:57 UTC (permalink / raw)
To: Sudeep Holla
Cc: linux-kernel, moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE
> > Or consider part of the SCMI-SMC transport API that output arg a0
> > shall be 0 on success, SMCCC_RET_NOT_SUPPORTED if function ID is not
> > supported and any non-zero value for non-generic **error** codes.
> >
>
> I prefer that. Anyways I will check and if anything changes I will ping
> back on this thread.
I don't have a strong opinion on whether considering or not 0 as
success, for whatever the function ID used here for SCMI message
notification.
We can assume at least 0 is default returned in a0 when the function
ID is used in SCMI SMC transport.
Thanks for the feedback.
> --
> Regards,
> Sudeep
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-05-15 9:57 UTC | newest]
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2020-05-14 8:24 [PATCH] firmware: arm_scmi: fix SMCCC_RET_NOT_SUPPORTED management Etienne Carriere
2020-05-14 14:29 ` Sudeep Holla
2020-05-14 15:06 ` Etienne Carriere
2020-05-15 9:34 ` Sudeep Holla
2020-05-15 9:57 ` Etienne Carriere
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