[PATCH] ARC: guard dsp early init against non ARCv2

[PATCH] ARC: guard dsp early init against non ARCv2

[Eugeniy Paltsev]

As of today we guard early DSP init code with
ARC_AUX_DSP_BUILD (0x7A) BCR check to verify that we have
CPU with DSP configured. However that's not enough as in
ARCv1 CPU the same BCR (0x7A) is used for checking MUL/MAC
instructions presence.

So, let's guard DSP early init against non ARCv2.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
 arch/arc/include/asm/dsp-impl.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
index e1aa212ca6eb..e64d945ae7df 100644
--- a/arch/arc/include/asm/dsp-impl.h
+++ b/arch/arc/include/asm/dsp-impl.h
@@ -15,12 +15,14 @@
 
 /* clobbers r5 register */
 .macro DSP_EARLY_INIT
+#if defined(CONFIG_ISA_ARCV2)
 	lr	r5, [ARC_AUX_DSP_BUILD]
 	bmsk	r5, r5, 7
 	breq    r5, 0, 1f
 	mov	r5, DSP_CTRL_DISABLED_ALL
 	sr	r5, [ARC_AUX_DSP_CTRL]
 1:
+#endif
 .endm
 
 /* clobbers r10, r11 registers pair */
-- 
2.21.1

Re: [PATCH] ARC: guard dsp early init against non ARCv2

[Vineet Gupta]

On 4/28/20 11:50 AM, Eugeniy Paltsev wrote:
> As of today we guard early DSP init code with
> ARC_AUX_DSP_BUILD (0x7A) BCR check to verify that we have
> CPU with DSP configured. However that's not enough as in
> ARCv1 CPU the same BCR (0x7A) is used for checking MUL/MAC
> instructions presence.
>
> So, let's guard DSP early init against non ARCv2.
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
>  arch/arc/include/asm/dsp-impl.h | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
> index e1aa212ca6eb..e64d945ae7df 100644
> --- a/arch/arc/include/asm/dsp-impl.h
> +++ b/arch/arc/include/asm/dsp-impl.h
> @@ -15,12 +15,14 @@
>  
>  /* clobbers r5 register */
>  .macro DSP_EARLY_INIT
> +#if defined(CONFIG_ISA_ARCV2)

ifdef is the canonical way for a single macro to check.

Also, this needs to be finer grained, i.e. CONFIG_ARC_DSP_KERNEL which is already
tied to ARCV2 only configs.

>  	lr	r5, [ARC_AUX_DSP_BUILD]
>  	bmsk	r5, r5, 7
>  	breq    r5, 0, 1f
>  	mov	r5, DSP_CTRL_DISABLED_ALL
>  	sr	r5, [ARC_AUX_DSP_CTRL]
>  1:
> +#endif
>  .endm
>  
>  /* clobbers r10, r11 registers pair */

RE: [PATCH] ARC: guard dsp early init against non ARCv2

[Jose Abreu]

From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Date: Apr/28/2020, 19:50:24 (UTC+00:00)

> As of today we guard early DSP init code with
> ARC_AUX_DSP_BUILD (0x7A) BCR check to verify that we have
> CPU with DSP configured. However that's not enough as in
> ARCv1 CPU the same BCR (0x7A) is used for checking MUL/MAC
> instructions presence.
> 
> So, let's guard DSP early init against non ARCv2.
> 
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>

Reported-by: Angelo Ribeiro 
<angelor@synopsys.com>

---
Thanks,
Jose Miguel Abreu

RE: [PATCH] ARC: guard dsp early init against non ARCv2

[Angelo Ribeiro]

Hi Eugeniy,

Tested okay on a ARCv1.

Thanks
Angelo

Tested-by: Angelo Ribeiro <angelo.ribeiro@synopsys.com>

From: Jose Abreu <joabreu@synopsys.com>
Date: Wed, Apr 29, 2020 at 07:19:55

> From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> Date: Apr/28/2020, 19:50:24 (UTC+00:00)
> 
> > As of today we guard early DSP init code with
> > ARC_AUX_DSP_BUILD (0x7A) BCR check to verify that we have
> > CPU with DSP configured. However that's not enough as in
> > ARCv1 CPU the same BCR (0x7A) is used for checking MUL/MAC
> > instructions presence.
> > 
> > So, let's guard DSP early init against non ARCv2.
> > 
> > Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> 
> Reported-by: Angelo Ribeiro 
> <angelor@synopsys.com>
> 
> ---
> Thanks,
> Jose Miguel Abreu

Re: [PATCH] ARC: guard dsp early init against non ARCv2

[Eugeniy Paltsev]

Hi Vineet, 

> From: Vineet Gupta <vgupta@synopsys.com>
> Sent: Tuesday, April 28, 2020 22:46
> To: Eugeniy Paltsev; linux-snps-arc@lists.infradead.org
> Cc: Alexey Brodkin; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] ARC: guard dsp early init against non ARCv2
> 
> On 4/28/20 11:50 AM, Eugeniy Paltsev wrote:
> > As of today we guard early DSP init code with
> > ARC_AUX_DSP_BUILD (0x7A) BCR check to verify that we have
> > CPU with DSP configured. However that's not enough as in
> > ARCv1 CPU the same BCR (0x7A) is used for checking MUL/MAC
> > instructions presence.
> >
> > So, let's guard DSP early init against non ARCv2.
> >
> > Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> > ---
> >  arch/arc/include/asm/dsp-impl.h | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
> > index e1aa212ca6eb..e64d945ae7df 100644
> > --- a/arch/arc/include/asm/dsp-impl.h
> > +++ b/arch/arc/include/asm/dsp-impl.h
> > @@ -15,12 +15,14 @@
> >
> >  /* clobbers r5 register */
> >  .macro DSP_EARLY_INIT
> > +#if defined(CONFIG_ISA_ARCV2)
> 
> ifdef is the canonical way for a single macro to check.
> 
> Also, this needs to be finer grained, i.e. CONFIG_ARC_DSP_KERNEL which is already
> tied to ARCV2 only configs.

We shouldn't limit the scope of this code part [dsp early init] to the cases
were DSP support is enabled in kconfig - and that is the reason why this code
initially was guarded with BCR check only.

So, I change the check to

#if defined(CONFIG_ARC_DSP_HANDLED) || defined(CONFIG_ARC_DSP_NONE)

which is actually the equivalent to

#if defined(CONFIG_ISA_ARCV2)

but I don't think it's worth thing to do.

> 
> >       lr      r5, [ARC_AUX_DSP_BUILD]
> >       bmsk    r5, r5, 7
> >       breq    r5, 0, 1f
> >       mov     r5, DSP_CTRL_DISABLED_ALL
> >       sr      r5, [ARC_AUX_DSP_CTRL]
> >  1:
> > +#endif
> >  .endm
> >
> >  /* clobbers r10, r11 registers pair */

---
 Eugeniy Paltsev

Re: [PATCH] ARC: guard dsp early init against non ARCv2

[Vineet Gupta]

On 4/29/20 10:12 AM, Eugeniy Paltsev wrote:
> Hi Vineet, 
>
>> From: Vineet Gupta <vgupta@synopsys.com>
>> Sent: Tuesday, April 28, 2020 22:46
>> To: Eugeniy Paltsev; linux-snps-arc@lists.infradead.org
>> Cc: Alexey Brodkin; linux-kernel@vger.kernel.org
>> Subject: Re: [PATCH] ARC: guard dsp early init against non ARCv2
>>
>> On 4/28/20 11:50 AM, Eugeniy Paltsev wrote:
>>> As of today we guard early DSP init code with
>>> ARC_AUX_DSP_BUILD (0x7A) BCR check to verify that we have
>>> CPU with DSP configured. However that's not enough as in
>>> ARCv1 CPU the same BCR (0x7A) is used for checking MUL/MAC
>>> instructions presence.
>>>
>>> So, let's guard DSP early init against non ARCv2.
>>>
>>> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
>>> ---
>>>  arch/arc/include/asm/dsp-impl.h | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
>>> index e1aa212ca6eb..e64d945ae7df 100644
>>> --- a/arch/arc/include/asm/dsp-impl.h
>>> +++ b/arch/arc/include/asm/dsp-impl.h
>>> @@ -15,12 +15,14 @@
>>>
>>>  /* clobbers r5 register */
>>>  .macro DSP_EARLY_INIT
>>> +#if defined(CONFIG_ISA_ARCV2)
>> ifdef is the canonical way for a single macro to check.
>>
>> Also, this needs to be finer grained, i.e. CONFIG_ARC_DSP_KERNEL which is already
>> tied to ARCV2 only configs.
> We shouldn't limit the scope of this code part [dsp early init] to the cases
> were DSP support is enabled in kconfig - and that is the reason why this code
> initially was guarded with BCR check only.
>
> So, I change the check to
>
> #if defined(CONFIG_ARC_DSP_HANDLED) || defined(CONFIG_ARC_DSP_NONE)

You are right. It needs to be disabled if the hardware exists independent of Kconfig.

> which is actually the equivalent to
>
> #if defined(CONFIG_ISA_ARCV2)
>
> but I don't think it's worth thing to do.

Agree.

-Vineet