2020-07-31 04:27:14

by Florian Fainelli

[permalink] [raw]
Subject: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs

Disable pref 30 by utilizing the standard quirk method and matching the
affected SoCs: 7344, 7346, 7425.

Signed-off-by: Florian Fainelli <[email protected]>
---
arch/mips/bmips/setup.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
index 19308df5f577..df0efea12611 100644
--- a/arch/mips/bmips/setup.c
+++ b/arch/mips/bmips/setup.c
@@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
bcm63xx_fixup_cpu1();
}

+static void bmips5000_pref30_quirk(void)
+{
+ __asm__ __volatile__(
+ " li $8, 0x5a455048\n"
+ " .word 0x4088b00f\n" /* mtc0 $8, $22, 15 */
+ " nop; nop; nop\n"
+ " .word 0x4008b008\n" /* mfc0 $8, $22, 8 */
+ /* disable "pref 30" on buggy CPUs */
+ " lui $9, 0x0800\n"
+ " or $8, $9\n"
+ " .word 0x4088b008\n" /* mtc0 $8, $22, 8 */
+ : : : "$8", "$9");
+}
+
static const struct bmips_quirk bmips_quirk_list[] = {
{ "brcm,bcm3368", &bcm6358_quirks },
{ "brcm,bcm3384-viper", &bcm3384_viper_quirks },
@@ -120,6 +134,9 @@ static const struct bmips_quirk bmips_quirk_list[] = {
{ "brcm,bcm6368", &bcm6368_quirks },
{ "brcm,bcm63168", &bcm6368_quirks },
{ "brcm,bcm63268", &bcm6368_quirks },
+ { "brcm,bcm7344", &bmips5000_pref30_quirk },
+ { "brcm,bcm7346", &bmips5000_pref30_quirk },
+ { "brcm,bcm7425", &bmips5000_pref30_quirk },
{ },
};

--
2.25.1


2020-07-31 09:10:42

by Thomas Bogendoerfer

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs

On Thu, Jul 30, 2020 at 09:24:01PM -0700, Florian Fainelli wrote:
> Disable pref 30 by utilizing the standard quirk method and matching the
> affected SoCs: 7344, 7346, 7425.
>
> Signed-off-by: Florian Fainelli <[email protected]>
> ---
> arch/mips/bmips/setup.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
> index 19308df5f577..df0efea12611 100644
> --- a/arch/mips/bmips/setup.c
> +++ b/arch/mips/bmips/setup.c
> @@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
> bcm63xx_fixup_cpu1();
> }
>
> +static void bmips5000_pref30_quirk(void)
> +{
> + __asm__ __volatile__(
> + " li $8, 0x5a455048\n"
> + " .word 0x4088b00f\n" /* mtc0 $8, $22, 15 */
> + " nop; nop; nop\n"
> + " .word 0x4008b008\n" /* mfc0 $8, $22, 8 */
> + /* disable "pref 30" on buggy CPUs */
> + " lui $9, 0x0800\n"
> + " or $8, $9\n"
> + " .word 0x4088b008\n" /* mtc0 $8, $22, 8 */
> + : : : "$8", "$9");

what's the reason for not using mfc/mtc here ?

Thomas.

--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]

2020-07-31 10:36:04

by Jiaxun Yang

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs



?? 2020/7/31 ????12:24, Florian Fainelli д??:
> Disable pref 30 by utilizing the standard quirk method and matching the
> affected SoCs: 7344, 7346, 7425.
>
> Signed-off-by: Florian Fainelli <[email protected]>
> ---
> arch/mips/bmips/setup.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
> index 19308df5f577..df0efea12611 100644
> --- a/arch/mips/bmips/setup.c
> +++ b/arch/mips/bmips/setup.c
> @@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
> bcm63xx_fixup_cpu1();
> }
>
> +static void bmips5000_pref30_quirk(void)
> +{
> + __asm__ __volatile__(
> + " li $8, 0x5a455048\n"
> + " .word 0x4088b00f\n" /* mtc0 $8, $22, 15 */
> + " nop; nop; nop\n"
> + " .word 0x4008b008\n" /* mfc0 $8, $22, 8 */
> + /* disable "pref 30" on buggy CPUs */
> + " lui $9, 0x0800\n"
> + " or $8, $9\n"
> + " .word 0x4088b008\n" /* mtc0 $8, $22, 8 */
> + : : : "$8", "$9");
> +}
Hi,

Is there any toolchain issue blocking read_c0_**** family helpers being
used?

Use .word looks unreasonable.

Thanks

- Jiaxun

> +
> static const struct bmips_quirk bmips_quirk_list[] = {
> { "brcm,bcm3368", &bcm6358_quirks },
> { "brcm,bcm3384-viper", &bcm3384_viper_quirks },
> @@ -120,6 +134,9 @@ static const struct bmips_quirk bmips_quirk_list[] = {
> { "brcm,bcm6368", &bcm6368_quirks },
> { "brcm,bcm63168", &bcm6368_quirks },
> { "brcm,bcm63268", &bcm6368_quirks },
> + { "brcm,bcm7344", &bmips5000_pref30_quirk },
> + { "brcm,bcm7346", &bmips5000_pref30_quirk },
> + { "brcm,bcm7425", &bmips5000_pref30_quirk },
> { },
> };
>

2020-07-31 22:50:28

by Florian Fainelli

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs

On 7/31/20 2:05 AM, Thomas Bogendoerfer wrote:
> On Thu, Jul 30, 2020 at 09:24:01PM -0700, Florian Fainelli wrote:
>> Disable pref 30 by utilizing the standard quirk method and matching the
>> affected SoCs: 7344, 7346, 7425.
>>
>> Signed-off-by: Florian Fainelli <[email protected]>
>> ---
>> arch/mips/bmips/setup.c | 17 +++++++++++++++++
>> 1 file changed, 17 insertions(+)
>>
>> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
>> index 19308df5f577..df0efea12611 100644
>> --- a/arch/mips/bmips/setup.c
>> +++ b/arch/mips/bmips/setup.c
>> @@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
>> bcm63xx_fixup_cpu1();
>> }
>>
>> +static void bmips5000_pref30_quirk(void)
>> +{
>> + __asm__ __volatile__(
>> + " li $8, 0x5a455048\n"
>> + " .word 0x4088b00f\n" /* mtc0 $8, $22, 15 */
>> + " nop; nop; nop\n"
>> + " .word 0x4008b008\n" /* mfc0 $8, $22, 8 */
>> + /* disable "pref 30" on buggy CPUs */
>> + " lui $9, 0x0800\n"
>> + " or $8, $9\n"
>> + " .word 0x4088b008\n" /* mtc0 $8, $22, 8 */
>> + : : : "$8", "$9");
>
> what's the reason for not using mfc/mtc here ?

See my response to Jiaxun, thanks!
--
Florian

2020-07-31 22:52:19

by Florian Fainelli

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs

On 7/31/20 3:34 AM, Jiaxun Yang wrote:
>
>
> 在 2020/7/31 下午12:24, Florian Fainelli 写道:
>> Disable pref 30 by utilizing the standard quirk method and matching the
>> affected SoCs: 7344, 7346, 7425.
>>
>> Signed-off-by: Florian Fainelli <[email protected]>
>> ---
>>   arch/mips/bmips/setup.c | 17 +++++++++++++++++
>>   1 file changed, 17 insertions(+)
>>
>> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
>> index 19308df5f577..df0efea12611 100644
>> --- a/arch/mips/bmips/setup.c
>> +++ b/arch/mips/bmips/setup.c
>> @@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
>>       bcm63xx_fixup_cpu1();
>>   }
>>   +static void bmips5000_pref30_quirk(void)
>> +{
>> +    __asm__ __volatile__(
>> +    "    li    $8, 0x5a455048\n"
>> +    "    .word    0x4088b00f\n"    /* mtc0 $8, $22, 15 */
>> +    "    nop; nop; nop\n"
>> +    "    .word    0x4008b008\n"    /* mfc0 $8, $22, 8 */
>> +    /* disable "pref 30" on buggy CPUs */
>> +    "    lui    $9, 0x0800\n"
>> +    "    or    $8, $9\n"
>> +    "    .word    0x4088b008\n"    /* mtc0 $8, $22, 8 */
>> +    : : : "$8", "$9");
>> +}
> Hi,
>
> Is there any toolchain issue blocking read_c0_**** family helpers being
> used?
>
> Use .word looks unreasonable.

Yes, the assembler would be choking on the custom $22 selector, however
this patch should not be necessary given that the boot loader (CFE)
should have long been updated by now to disable pref 30.

Thanks
--
Florian

2020-08-03 11:32:17

by Thomas Bogendoerfer

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs

On Fri, Jul 31, 2020 at 03:49:28PM -0700, Florian Fainelli wrote:
> On 7/31/20 3:34 AM, Jiaxun Yang wrote:
> >
> >
> > 在 2020/7/31 下午12:24, Florian Fainelli 写道:
> >> Disable pref 30 by utilizing the standard quirk method and matching the
> >> affected SoCs: 7344, 7346, 7425.
> >>
> >> Signed-off-by: Florian Fainelli <[email protected]>
> >> ---
> >>   arch/mips/bmips/setup.c | 17 +++++++++++++++++
> >>   1 file changed, 17 insertions(+)
> >>
> >> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
> >> index 19308df5f577..df0efea12611 100644
> >> --- a/arch/mips/bmips/setup.c
> >> +++ b/arch/mips/bmips/setup.c
> >> @@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
> >>       bcm63xx_fixup_cpu1();
> >>   }
> >>   +static void bmips5000_pref30_quirk(void)
> >> +{
> >> +    __asm__ __volatile__(
> >> +    "    li    $8, 0x5a455048\n"
> >> +    "    .word    0x4088b00f\n"    /* mtc0 $8, $22, 15 */
> >> +    "    nop; nop; nop\n"
> >> +    "    .word    0x4008b008\n"    /* mfc0 $8, $22, 8 */
> >> +    /* disable "pref 30" on buggy CPUs */
> >> +    "    lui    $9, 0x0800\n"
> >> +    "    or    $8, $9\n"
> >> +    "    .word    0x4088b008\n"    /* mtc0 $8, $22, 8 */
> >> +    : : : "$8", "$9");
> >> +}
> > Hi,
> >
> > Is there any toolchain issue blocking read_c0_**** family helpers being
> > used?
> >
> > Use .word looks unreasonable.
>
> Yes, the assembler would be choking on the custom $22 selector, however

I guess you meant selector 8 and 15. If BMIPS has a 4 bit selector field
it might be good to do a binutils patch supporting it.

> this patch should not be necessary given that the boot loader (CFE)
> should have long been updated by now to disable pref 30.

so, should I add it or drop it ?

Thomas.

--
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea. [ RFC1925, 2.3 ]

2020-08-03 17:17:34

by Florian Fainelli

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs



On 8/3/2020 4:30 AM, Thomas Bogendoerfer wrote:
> On Fri, Jul 31, 2020 at 03:49:28PM -0700, Florian Fainelli wrote:
>> On 7/31/20 3:34 AM, Jiaxun Yang wrote:
>>>
>>>
>>> 在 2020/7/31 下午12:24, Florian Fainelli 写道:
>>>> Disable pref 30 by utilizing the standard quirk method and matching the
>>>> affected SoCs: 7344, 7346, 7425.
>>>>
>>>> Signed-off-by: Florian Fainelli <[email protected]>
>>>> ---
>>>>   arch/mips/bmips/setup.c | 17 +++++++++++++++++
>>>>   1 file changed, 17 insertions(+)
>>>>
>>>> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
>>>> index 19308df5f577..df0efea12611 100644
>>>> --- a/arch/mips/bmips/setup.c
>>>> +++ b/arch/mips/bmips/setup.c
>>>> @@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
>>>>       bcm63xx_fixup_cpu1();
>>>>   }
>>>>   +static void bmips5000_pref30_quirk(void)
>>>> +{
>>>> +    __asm__ __volatile__(
>>>> +    "    li    $8, 0x5a455048\n"
>>>> +    "    .word    0x4088b00f\n"    /* mtc0 $8, $22, 15 */
>>>> +    "    nop; nop; nop\n"
>>>> +    "    .word    0x4008b008\n"    /* mfc0 $8, $22, 8 */
>>>> +    /* disable "pref 30" on buggy CPUs */
>>>> +    "    lui    $9, 0x0800\n"
>>>> +    "    or    $8, $9\n"
>>>> +    "    .word    0x4088b008\n"    /* mtc0 $8, $22, 8 */
>>>> +    : : : "$8", "$9");
>>>> +}
>>> Hi,
>>>
>>> Is there any toolchain issue blocking read_c0_**** family helpers being
>>> used?
>>>
>>> Use .word looks unreasonable.
>>
>> Yes, the assembler would be choking on the custom $22 selector, however
>
> I guess you meant selector 8 and 15. If BMIPS has a 4 bit selector field
> it might be good to do a binutils patch supporting it.

Yes, sorry that is what I meant. I don't think an assembler patch makes
sense at this point given this is an isolated use, and there is not just
binutils these days, the Clang/LLVM integrated assembler would also need
to be supported, and then we would need to have the kernel say: I
require this minimum version to support the customer selectors, not
worth the trouble if you ask me.

>
>> this patch should not be necessary given that the boot loader (CFE)
>> should have long been updated by now to disable pref 30.
>
> so, should I add it or drop it ?

You can drop it and I would resubmit it with feedback addressed if this
later comes back.
--
Florian

2020-08-05 02:07:23

by Maciej W. Rozycki

[permalink] [raw]
Subject: Re: [PATCH] MIPS: BMIPS: Disable pref 30 for buggy CPUs

On Mon, 3 Aug 2020, Florian Fainelli wrote:

> >>>> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
> >>>> index 19308df5f577..df0efea12611 100644
> >>>> --- a/arch/mips/bmips/setup.c
> >>>> +++ b/arch/mips/bmips/setup.c
> >>>> @@ -110,6 +110,20 @@ static void bcm6368_quirks(void)
> >>>>       bcm63xx_fixup_cpu1();
> >>>>   }
> >>>>   +static void bmips5000_pref30_quirk(void)
> >>>> +{
> >>>> +    __asm__ __volatile__(
> >>>> +    "    li    $8, 0x5a455048\n"
> >>>> +    "    .word    0x4088b00f\n"    /* mtc0 $8, $22, 15 */
> >>>> +    "    nop; nop; nop\n"
> >>>> +    "    .word    0x4008b008\n"    /* mfc0 $8, $22, 8 */
> >>>> +    /* disable "pref 30" on buggy CPUs */
> >>>> +    "    lui    $9, 0x0800\n"
> >>>> +    "    or    $8, $9\n"
> >>>> +    "    .word    0x4088b008\n"    /* mtc0 $8, $22, 8 */
> >>>> +    : : : "$8", "$9");
> >>>> +}
> >>> Hi,
> >>>
> >>> Is there any toolchain issue blocking read_c0_**** family helpers being
> >>> used?
> >>>
> >>> Use .word looks unreasonable.
> >>
> >> Yes, the assembler would be choking on the custom $22 selector, however
> >
> > I guess you meant selector 8 and 15. If BMIPS has a 4 bit selector field
> > it might be good to do a binutils patch supporting it.
>
> Yes, sorry that is what I meant. I don't think an assembler patch makes
> sense at this point given this is an isolated use, and there is not just
> binutils these days, the Clang/LLVM integrated assembler would also need
> to be supported, and then we would need to have the kernel say: I
> require this minimum version to support the customer selectors, not
> worth the trouble if you ask me.

Well, I asked for a GAS patch to add support 4.5 years ago, so by now and
9 binutils releases later it would have become fairly common. And then I
also suggested how to handle it in a robust way. Cf.
<https://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=alpine.DEB.2.00.1602092245180.15885%40tp.orcam.me.uk>.

Maciej