[PATCH 2/2] arch_timer: acpi: add hisi timer erratum data

[Marc Zyngier]

On 24/01/17 12:35, John Garry wrote:
> On 24/01/2017 11:32, Marc Zyngier wrote:
>> On 24/01/17 10:57, Mark Rutland wrote:
>>> On Tue, Jan 24, 2017 at 06:39:51PM +0800, Hanjun Guo wrote:
>>>> From: Hanjun Guo <hanjun.guo at linaro.org>
>>>>
>>>> Add hisilicon timer specific erratum fixes.
>>>>
>>>> Signed-off-by: Hanjun Guo <hanjun.guo at linaro.org>
>>>> ---
>>>>  drivers/clocksource/arm_arch_timer.c | 22 ++++++++++++++++++++++
>>>>  1 file changed, 22 insertions(+)
>>>>
>>>> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
>>>> index 80d6f76..3e62a09 100644
>>>> --- a/drivers/clocksource/arm_arch_timer.c
>>>> +++ b/drivers/clocksource/arm_arch_timer.c
>>>> @@ -1156,10 +1156,32 @@ struct gtdt_arch_timer_fixup {
>>>>  	void *context;
>>>>  };
>>>>
>>>> +#ifdef CONFIG_HISILICON_ERRATUM_161010101
>>>> +static void __init hisi_erratum_workaroud_enable(void *context)
>>>> +{
>>>> +	int i;
>>>> +
>>>> +	for (i = 0; i < ARRAY_SIZE(ool_workarounds); i++) {
>>>> +		if (!strcmp(context, ool_workarounds[i].id)) {
>>>> +			timer_unstable_counter_workaround = &ool_workarounds[i];
>>>> +			static_branch_enable(&arch_timer_read_ool_enabled);
>>>> +			pr_info("arch_timer: Enabling workaround for %s\n",
>>>> +				timer_unstable_counter_workaround->id);
>>>> +			break;
>>>> +		}
>>>> +	}
>>>> +}
>>>> +#endif
>>>> +
>>>>  /* note: this needs to be updated according to the doc of OEM ID
>>>>   * and TABLE ID for different board.
>>>>   */
>>>>  static struct gtdt_arch_timer_fixup arch_timer_quirks[] __initdata = {
>>>> +#ifdef CONFIG_HISILICON_ERRATUM_161010101
>>>> +	{"HISI  ", "HIP05   ", 0, &hisi_erratum_workaroud_enable, "hisilicon,erratum-161010101"},
>>>> +	{"HISI  ", "HIP06   ", 0, &hisi_erratum_workaroud_enable, "hisilicon,erratum-161010101"},
>>>> +	{"HISI  ", "HIP07   ", 0, &hisi_erratum_workaroud_enable, "hisilicon,erratum-161010101"},
>>>> +#endif
>>>>  };
>>>
>>> NAK. This duplicates logic unnecessarily (for enabling the workaround),
>>> and (ab)uses the id, which was intended to be specific to DT (since it
>>> is a DT property name).
>>
>> Agreed, that's properly revolting.
>>
>>> We should split the matching from the particular workaround (and
>>> enabling thereof), so that we can go straight from ACPI match to
>>> workaround (without having to use the DT id in this manner), and don't
>>> have to duplicate the logic to enable the workaround.
>>>
>>> I believe Marc is looking at some rework in this area which may enable
>>> this, so please wait for that to appear.
>>
>> Yeah, I'm implementing a semi-flexible way to add new quirk types, and
>> the last thing I want to see is two (or more) tables describing the same
>> thing.
>>
> 
> FYI, We have a similar requirement to enable a quirk on the GICv3 ITS 
> driver. For that driver the current quirk framework relies on matching 
> the IIDR, which is not properly populated for our hardware. So will this 
> framework cover this/many/all drivers?

Most probably not. Each driver has its own requirements, and it is
unlikely that the timer's fit with the GIC's. But maybe we can use
similar patterns.

> Shameer has prepared the patchset for this quirk - should it send it? It 
> will be rejected for the same reason as this one, but at least it is 
> more reference for this framework wishlist.

Well, try and see it the other way around. If you don't send the patch,
it can't be rejected! ;-) Now, if you're genuinely interested in finding
out what I think of it, and possibly some advise on how to address the
issue, then please post it.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...