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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Fri, 13 May 2016 15:46:42 +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

On 13/05/16 15:19, Ludovic Desroches wrote:
> On Fri, May 13, 2016 at 02:37:21PM +0300, Adrian Hunter wrote:
>> + 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?
>>
> 
> Yes, I din't wake up on card event without this patch.
> 
>>>
>>> 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.
> 
> I'll add it.
> 
>>
>>>
>>> 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?
>>
> 
> I only use wakeup events and not irqs in system PM (patches for
> sdhci-of-at91 are not sent yet, I am waiting for the inclusion of other
> patches).

It doesn't hurt to say in the commit message what driver or hardware needed
the change.

> 
> What I mean is that if we want to wake up from irqs, it could be safer and
> clearer to set explicitely SDHCI_INT_ENABLE and SDHCI_SIGNAL_ENABLE in
> sdhci_enable_irq_wakeups(). It is just a thought and not needed for this
> patch.
> 
>>>
>>> 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.
>>
> 
> I thought it will be better to have wakeup_val and irq_val instead of
> val and irq_val. That's why I renamed it while introducing irq_val.

val and irq_val are fine.

> 
>>> +	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);
>>>  
>>>
>>
>