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SubjectRe: [PATCH v3 5/5] irqchip: qcom-pdc: Reset all pdc interrupts during init
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Hi,

On 7/14/2020 3:47 AM, Doug Anderson wrote:
> Hi,
>
> On Mon, Jun 22, 2020 at 2:33 AM Maulik Shah <mkshah@codeaurora.org> wrote:
>> Clear previous kernel's configuration during init by resetting
>> all interrupts in enable bank to zero.
>>
>> Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
>> ---
>> drivers/irqchip/qcom-pdc.c | 13 +++++++++++++
>> 1 file changed, 13 insertions(+)
>>
>> diff --git a/drivers/irqchip/qcom-pdc.c b/drivers/irqchip/qcom-pdc.c
>> index 8beb6f7..11a9d3a 100644
>> --- a/drivers/irqchip/qcom-pdc.c
>> +++ b/drivers/irqchip/qcom-pdc.c
>> @@ -19,6 +19,7 @@
>> #include <linux/slab.h>
>> #include <linux/types.h>
>>
>> +#define PDC_MAX_IRQS_PER_REG 32
>> #define PDC_MAX_IRQS 168
>> #define PDC_MAX_GPIO_IRQS 256
>>
>> @@ -339,6 +340,7 @@ static const struct irq_domain_ops qcom_pdc_gpio_ops = {
>> static int pdc_setup_pin_mapping(struct device_node *np)
>> {
>> int ret, n;
>> + u32 reg, max_regs, max_pins = 0;
>>
>> n = of_property_count_elems_of_size(np, "qcom,pdc-ranges", sizeof(u32));
>> if (n <= 0 || n % 3)
>> @@ -367,8 +369,19 @@ static int pdc_setup_pin_mapping(struct device_node *np)
>> &pdc_region[n].cnt);
>> if (ret)
>> return ret;
>> + max_pins += pdc_region[n].cnt;
>> }
>>
>> + if (max_pins > PDC_MAX_IRQS)
>> + return -EINVAL;
>> +
>> + max_regs = max_pins / PDC_MAX_IRQS_PER_REG;
>> + if (max_pins % PDC_MAX_IRQS_PER_REG)
>> + max_regs++;
> nit: max_regs = DIV_ROUND_UP(max_pins, PDC_MAX_IRQS_PER_REG)
>
>
>> + for (reg = 0; reg < max_regs; reg++)
>> + pdc_reg_write(IRQ_ENABLE_BANK, reg, 0);
> This doesn't feel correct to me, but maybe I'm misunderstanding the
> hardware (I don't think I have access to a reference manual). Looking
> at the example in the bindings, I see:
>
> qcom,pdc-ranges = <0 512 94>, <94 641 15>, <115 662 7>;
>
> In that example we have mappings for PDC ports:
> 0 - 93 (count = 94)
> 94 - 108 (count = 15)
> 115 - 121 (count = 7)
>
> Notice the slight discontinuity there. I presume that discontinuity
> is normal / allowed? If so, if there is enough of it then I think
> your math could be wrong, though with the example you get lucky and it
> works out OK. It's easy to see the problem with a slightly different
> example: Imagine that you had this:
>
> 0 - 33 (count = 34)
> 94 - 108 (count = 15)
> 115 - 121 (count = 7)
>
> ...now max_pins = 56 and max_regs = 2. So you'll init reg 0 and 1.
> ...but (IIUC) you actually should be initting 0, 1, 2, and 3.

Right, Thanks for cacthing this. I will fix in next revision.

Thanks,
Maulik

> I have no idea what might be in those discontinuous ranges and if it's
> always OK to clear, but (assuming it is) one fix is to put your
> clearing loop _inside_ the other "for" loop in this function, AKA:
>
> for (reg = pdc_region[n].pin_base / PDC_MAX_IRQS_PER_REG;
> reg < DIV_ROUND_UP(pdc_region[n].pin_base + pdc_region[n].cnt),
> PDC_MAX_IRQS_PER_REG)
> reg++)
>
> ...or another option is to keep track of the max "pin_base + cnt" and
> loop from 0 to there? I just don't know your hardware well enough to
> tell which would be right.

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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