linux-kernel - Re: [RESEND PATCH] mmc: sdhci: fix wakeup configuration

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Date:	Fri, 13 May 2016 14:37:21 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Ludovic Desroches <ludovic.desroches@...el.com>
Cc:	ulf.hansson@...aro.org, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org, nicolas.ferre@...el.com,
	Kevin Liu <kliu5@...vell.com>, Jialing Fu <jlfu@...vell.com>,
	Jisheng Zhang <jszhang@...vell.com>
Subject: Re: [RESEND PATCH] mmc: sdhci: fix wakeup configuration

+ cc some Marvell people because they added this code

On 13/05/16 12:27, Ludovic Desroches wrote:
> Activating wakeup event is not enough to get a wakeup signal. The
> corresponding events have to be enabled in the Interrupt Status Enable
> Register too.

That seems to follow the specification.  Did you find that you actually
needed this change to get it to work?

> 
> Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
> ---
> Hi,
> 
> I just updated sdhci_enable_irq_wakeups() not sdhci_disable_irq_wakeups()
> because I don't think it is necessary to configure SDHCI_INT_ENABLE at this
> step, it will be done with sdhci_init() or sdhci_enable_card_detection().

OK, but that should be in the commit message and commented in the code too.

> 
> While I was writing this patch, several questions came to my mind:
> - Is the naming correct? wakeup signal is not an irq. 'enable_irq_wakeups' can
>   be a bit confusing.

I don't support renaming things unless the names are really really bad.
These names are OK.

> - If we want to wakeup from irq, we may have to set SDHCI_INT_ENABLE and
>   SDHCI_SIGNAL_ENABLE and not rely on a previous configuration, isn't it?

I imagine the card interrupt will occur when it is enabled.  I don't know
about card insert / remove.

What works for you?

> 
> Regards
> 
> Ludovic
> 
>  drivers/mmc/host/sdhci.c | 26 ++++++++++++++++++--------
>  1 file changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index b284924..6fc69ed 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2638,18 +2638,28 @@ static irqreturn_t sdhci_thread_irq(int irq, void *dev_id)
>  \*****************************************************************************/
>  
>  #ifdef CONFIG_PM
> +/*
> + * To enable wakeup events, the corresponding events have to be enabled in
> + * the Interrupt Status Enable register too. See 'Table 1-6: Wakeup Signal
> + * Table' in the SD Host Controller Standard Specification.
> + */
>  void sdhci_enable_irq_wakeups(struct sdhci_host *host)
>  {
> -	u8 val;
> -	u8 mask = SDHCI_WAKE_ON_INSERT | SDHCI_WAKE_ON_REMOVE
> -			| SDHCI_WAKE_ON_INT;
> +	u8 wakeup_val;
> +	u8 wakeup_mask = SDHCI_WAKE_ON_INSERT | SDHCI_WAKE_ON_REMOVE |
> +			 SDHCI_WAKE_ON_INT;

Please don't rename variables, or tidy-up code that you are not changing.

> +	u32 irq_val = SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE |
> +		      SDHCI_INT_CARD_INT;
>  
> -	val = sdhci_readb(host, SDHCI_WAKE_UP_CONTROL);
> -	val |= mask ;

These 2 line are actually unchanged.

> +	wakeup_val = sdhci_readb(host, SDHCI_WAKE_UP_CONTROL);
> +	wakeup_val |= wakeup_mask;
>  	/* Avoid fake wake up */
> -	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
> -		val &= ~(SDHCI_WAKE_ON_INSERT | SDHCI_WAKE_ON_REMOVE);
> -	sdhci_writeb(host, val, SDHCI_WAKE_UP_CONTROL);
> +	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) {
> +		wakeup_val &= ~(SDHCI_WAKE_ON_INSERT | SDHCI_WAKE_ON_REMOVE);
> +		irq_val &= ~(SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE);
> +	}
> +	sdhci_writeb(host, wakeup_val, SDHCI_WAKE_UP_CONTROL);
> +	sdhci_writel(host, irq_val, SDHCI_INT_ENABLE);
>  }
>  EXPORT_SYMBOL_GPL(sdhci_enable_irq_wakeups);
>  
>