Re: [PATCH 5/5] sdhci: Add quirk for delayed IRQ ACK

[Jeremy McNicoll <jmcnicol-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 2016-11-22 8:12 PM, Jisheng Zhang wrote:
> On Tue, 22 Nov 2016 19:48:56 -0800 Jeremy McNicoll wrote:
>
>> On 2016-11-22 7:36 PM, Jisheng Zhang wrote:
>>> On Tue, 22 Nov 2016 17:09:48 -0800
>>> Jeremy McNicoll <jeremymc-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
>>>
>>>> On msm8992 it has been observed that IRQs were not getting
>>>> ACK'd correctly when clocked at speeds greater than 400KHz.
>>>>
>>>> Signed-off-by: Jeremy McNicoll <jeremymc-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>>>> ---
>>>>  drivers/mmc/host/sdhci-msm.c |  7 +++++++
>>>>  drivers/mmc/host/sdhci.c     | 12 ++++++++++--
>>>>  drivers/mmc/host/sdhci.h     |  2 ++
>>>>  3 files changed, 19 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
>>>> index 1fcda96..459003c 100644
>>>> --- a/drivers/mmc/host/sdhci-msm.c
>>>> +++ b/drivers/mmc/host/sdhci-msm.c
>>>> @@ -1303,6 +1303,13 @@ static int sdhci_msm_probe(struct platform_device *pdev)
>>>>  			       CORE_VENDOR_SPEC_CAPABILITIES0);
>>>>  	}
>>>>
>>>> +	/* Enable delayed IRQ handling workaround on 8992 */
>>>> +	if (core_major == 1 && core_minor == 0x3e) {
>>>> +		/* Add 40us delay in interrupt handler when operating
>>>> +		 * at initialization frequency of 400KHz. */
>>>> +		host->quirks2 |= SDHCI_QUIRK2_SLOW_INT_CLR;
>>>> +	}
>>>> +
>>>>  	/* Setup IRQ for handling power/voltage tasks with PMIC */
>>>>  	msm_host->pwr_irq = platform_get_irq_byname(pdev, "pwr_irq");
>>>>  	if (msm_host->pwr_irq < 0) {
>>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>>> index 5911f98..c1aae22 100644
>>>> --- a/drivers/mmc/host/sdhci.c
>>>> +++ b/drivers/mmc/host/sdhci.c
>>>> @@ -2703,11 +2703,19 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
>>>>  			result = IRQ_WAKE_THREAD;
>>>>  		}
>>>>
>>>> -		if (intmask & SDHCI_INT_CMD_MASK)
>>>> +		if (intmask & SDHCI_INT_CMD_MASK) {
>>>> +			if ((host->quirks2 & SDHCI_QUIRK2_SLOW_INT_CLR) && (host->clock <= 400000)) {
>>>> +				udelay(40);
>>>> +			}
>>>>  			sdhci_cmd_irq(host, intmask & SDHCI_INT_CMD_MASK);
>>>> +		}
>>>>
>>>> -		if (intmask & SDHCI_INT_DATA_MASK)
>>>> +		if (intmask & SDHCI_INT_DATA_MASK) {
>>>> +			if ((host->quirks2 & SDHCI_QUIRK2_SLOW_INT_CLR) && (host->clock <= 400000)) {
>>>> +				udelay(40);
>>>> +			}
>>>>  			sdhci_data_irq(host, intmask & SDHCI_INT_DATA_MASK);
>>>> +		}
>>>>
>>>>  		if (intmask & SDHCI_INT_BUS_POWER)
>>>>  			pr_err("%s: Card is consuming too much power!\n",
>>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>>> index c055e24..5f8301e 100644
>>>> --- a/drivers/mmc/host/sdhci.h
>>>> +++ b/drivers/mmc/host/sdhci.h
>>>> @@ -24,6 +24,8 @@
>>>>   * Controller registers
>>>>   */
>>>>
>>>> +#define SDHCI_QUIRK2_SLOW_INT_CLR	(1<<5)
>>>
>>> IIRC, new quirk isn't allowed now.
>>>
>>
>> Why not?
>
> IIRC, mmc subsystem will behave as a lib in the long run, so the community
> and developers call for no new quirk. For your case, we may need to handle
> the udelay in sdhci-msm.c, export sdhci_irq as a helper function?
>
Thanks for the details and suggestions.  I am going to wait until the US
Thanksgiving (and cyber Monday) is over before I do any more.

-jeremy

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