Re: [PATCH V3 2/6] sdhci: Add quirk for delayed IRQ ACK

[Ritesh Harjani <riteshh@codeaurora.org>]

Hi Jeremy,

 From what I can see in codeaurora tree, quirk 
(SDHCI_QUIRK2_SLOW_INT_CLR) is only required for sdhci-msm with minor 
number 2B. I think this patch may not be relevant for msm8992 controller.
And as you have also mentioned in your V2, that even without this 
change, the detection is fine. The delay you are observing could be due 
to something else unless we are sure.

On reading history of this quirk, I see that this patch was a SW 
workaround for some HW issue in very initial controller.
This was fixed for later controllers.
For this reason, in my opinion we can drop this patch.

But, as we discussed on IRC, let's investigate more on your issue before 
finalizing on this patch for merging.

Regards
Ritesh

On 1/24/2017 3:06 PM, Jeremy McNicoll 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@redhat.com>
> ---
>  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 f3f3fb3..11dc389 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -1304,6 +1304,13 @@ 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 06dfac2..68a21a3 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2742,11 +2742,19 @@ 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 400f3a1..7fa1004 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)
> +
>  #define SDHCI_DMA_ADDRESS	0x00
>  #define SDHCI_ARGUMENT2		SDHCI_DMA_ADDRESS
>
>

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