linux-kernel - Re: [PATCH v2 09/16] mmc: sdhci: Add quirk to disable HW timeout

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Message-ID: <a7ba98cd-7a3c-00f9-bfaa-a982126c9185@ti.com>
Date:   Mon, 5 Mar 2018 15:00:52 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Tony Lindgren <tony@...mide.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        <linux-mmc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 09/16] mmc: sdhci: Add quirk to disable HW timeout

Hi Adrian,

On Monday 19 February 2018 02:21 PM, Adrian Hunter wrote:
> On 05/02/18 14:50, Kishon Vijay Abraham I wrote:
>> Add quirk to disable HW timeout if the requested timeout is more than
>> the maximum obtainable timeout.
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
>> ---
>>  drivers/mmc/host/sdhci.c | 12 ++++++++++++
>>  drivers/mmc/host/sdhci.h |  7 +++++++
>>  2 files changed, 19 insertions(+)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 070aff9c108f..1aa74b4682f3 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -735,6 +735,12 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
>>  		DBG("Too large timeout 0x%x requested for CMD%d!\n",
>>  		    count, cmd->opcode);
>>  		count = 0xE;
>> +		if (host->quirks2 & SDHCI_QUIRK2_DISABLE_HW_TIMEOUT) {
>> +			host->ier &= ~SDHCI_INT_DATA_TIMEOUT;
>> +			sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
>> +			sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
>> +			host->hw_timeout_disabled = true;
>> +		}
> 
> sdhci_calc_timeout() is really for calculations so please do this in
> sdhci_set_timeout() instead (i.e. change sdhci_calc_timeout() to return
> whether the timeout is too big).  Note that you need to cater for the "/*
> Unspecified timeout, assume max */" case and the
> SDHCI_QUIRK_BROKEN_TIMEOUT_VAL case.
> 
> Also if SDHCI_INT_DATA_TIMEOUT is not being disabled, check here to
> re-enable it and leave sdhci_request_done() alone. i.e.
> 
> 	else if (!(host->ier & SDHCI_INT_DATA_TIMEOUT)) {
> 		host->ier |= SDHCI_INT_DATA_TIMEOUT;
> 		sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
> 		sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
> 	}
> 
> Maybe make a separate subroutine for the update:
> 
> void sdhci_set_data_timeout_irq(struct sdhci_host *host, bool enable)
> {
> 	if (enable)
> 		host->ier |= SDHCI_INT_DATA_TIMEOUT;
> 	else
> 		host->ier &= ~SDHCI_INT_DATA_TIMEOUT;
> 	sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
> 	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
> }
> 
> 
>>  	}
>>  
>>  	return count;
>> @@ -2349,6 +2355,12 @@ static bool sdhci_request_done(struct sdhci_host *host)
>>  	}
>>  
>>  	sdhci_del_timer(host, mrq);
>> +	if (sdhci_data_line_cmd(mrq->cmd) && host->hw_timeout_disabled) {
>> +		host->ier |= SDHCI_INT_DATA_TIMEOUT;
>> +		sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
>> +		sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
>> +		host->hw_timeout_disabled = false;
>> +	}
>>  
>>  	/*
>>  	 * Always unmap the data buffers if they were mapped by
>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>> index afab26fd70e6..3a967a56fcc3 100644
>> --- a/drivers/mmc/host/sdhci.h
>> +++ b/drivers/mmc/host/sdhci.h
>> @@ -437,6 +437,11 @@ struct sdhci_host {
>>  #define SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN		(1<<15)
>>  /* Controller has CRC in 136 bit Command Response */
>>  #define SDHCI_QUIRK2_RSP_136_HAS_CRC			(1<<16)
>> +/*
>> + * Disable HW timeout if the requested timeout is more than the maximum
>> + * obtainable timeout
>> + */
>> +#define SDHCI_QUIRK2_DISABLE_HW_TIMEOUT			(1<<17)

Are you okay with the definition of this quirk? i.e this quirk is applied only
when the requested timeout is "more" than the maximum obtainable timeout.

By this way platforms can continue to use hardware timeout for smaller timeout
value.

Thanks
Kishon