Re: [PATCH 05/19] mmc: usdhi6rol0: Inform the mmc core about the maximum busy timeout

From: Jesper Nilsson <Jesper.Nilsson@axis.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Rui Miguel Silva" <rmfrfs@gmail.com>,
	"Johan Hovold" <johan@kernel.org>,
	"Alex Elder" <elder@kernel.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Jonathan Neuschäfer" <j.neuschaefer@gmx.net>,
	"Bruce Chang" <brucechang@via.com.tw>,
	"Harald Welte" <HaraldWelte@viatech.com>,
	"Alex Dubov" <oakad@yahoo.com>,
	"Sascha Sommer" <saschasommer@freenet.de>,
	"Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
	"mirq-linux@rere.qmqm.pl" <mirq-linux@rere.qmqm.pl>,
	"Jesper Nilsson" <Jesper.Nilsson@axis.com>,
	"Lars Persson" <Lars.Persson@axis.com>,
	"Paul Cercueil" <paul@crapouillou.net>,
	"Ludovic Desroches" <ludovic.desroches@microchip.com>,
	"Nicolas Ferre" <nicolas.ferre@microchip.com>
Subject: Re: [PATCH 05/19] mmc: usdhi6rol0: Inform the mmc core about the maximum busy timeout
Date: Wed, 15 Apr 2020 08:34:03 +0200	[thread overview]
Message-ID: <20200415063403.d3e3auv5engh555b@axis.com> (raw)
In-Reply-To: <20200414161413.3036-6-ulf.hansson@linaro.org>

On Tue, Apr 14, 2020 at 06:13:59PM +0200, Ulf Hansson wrote:
> Some commands uses R1B responses, which means the card may assert the DAT0
> line to signal busy for a period of time, after it has received the
> command. The mmc core normally specifies the busy period for the command in
> the cmd->busy_timeout. Ideally the driver should respect it, but that
> requires quite some update of the code, so let's defer that to someone with
> the HW at hand.
> 
> Instead, let's inform the mmc core about the maximum supported busy timeout
> in ->max_busy_timeout during ->probe(). This value corresponds to the fixed
> 4s timeout used by usdhi6rol0. In this way, we let the mmc core validate
> the needed timeout, which may lead to that it converts from a R1B into a R1
> response and then use CMD13 to poll for busy completion.
> 
> In other words, this change enables support for commands with longer busy
> periods than 4s, like erase (CMD38) for example.

Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>

> Cc: Lars Persson <lars.persson@axis.com>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>  drivers/mmc/host/usdhi6rol0.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/usdhi6rol0.c b/drivers/mmc/host/usdhi6rol0.c
> index 9a0b1e4e405d..369b8dee2e3d 100644
> --- a/drivers/mmc/host/usdhi6rol0.c
> +++ b/drivers/mmc/host/usdhi6rol0.c
> @@ -136,6 +136,8 @@
>  
>  #define USDHI6_MIN_DMA 64
>  
> +#define USDHI6_REQ_TIMEOUT_MS 4000
> +
>  enum usdhi6_wait_for {
>  	USDHI6_WAIT_FOR_REQUEST,
>  	USDHI6_WAIT_FOR_CMD,
> @@ -1763,7 +1765,12 @@ static int usdhi6_probe(struct platform_device *pdev)
>  	host		= mmc_priv(mmc);
>  	host->mmc	= mmc;
>  	host->wait	= USDHI6_WAIT_FOR_REQUEST;
> -	host->timeout	= msecs_to_jiffies(4000);
> +	host->timeout	= msecs_to_jiffies(USDHI6_REQ_TIMEOUT_MS);
> +	/*
> +	 * We use a fixed timeout of 4s, hence inform the core about it. A
> +	 * future improvement should instead respect the cmd->busy_timeout.
> +	 */
> +	mmc->max_busy_timeout = USDHI6_REQ_TIMEOUT_MS;
>  
>  	host->pinctrl = devm_pinctrl_get(&pdev->dev);
>  	if (IS_ERR(host->pinctrl)) {
> -- 
> 2.20.1
> 

/^JN - Jesper Nilsson
-- 
               Jesper Nilsson -- jesper.nilsson@axis.com