linux-kernel - Re: [patch 4/7] SDHCI: Add quirk for controller with no end-of-busy IRQ

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Message-ID: <20081114224114.5b5932a0@mjolnir.drzeus.cx>
Date:	Fri, 14 Nov 2008 22:41:14 +0100
From:	Pierre Ossman <drzeus-mmc@...eus.cx>
To:	Ben Dooks <ben-linux@...ff.org>
Cc:	linux-kernel@...r.kernel.org, sdhci-devel@...t.drzeus.cx,
	Ben Dooks <ben-linux@...ff.org>
Subject: Re: [patch 4/7] SDHCI: Add quirk for controller with no end-of-busy
 IRQ

On Mon, 03 Nov 2008 20:09:48 +0000
Ben Dooks <ben-linux@...ff.org> wrote:

> The Samsung SDHCI controller block seems to fail to generate an
> INT_DATA_END after the transfer has completed and the bus busy
> state finished. 
> 
> Changes in e809517f6fa5803a5a1cd56026f0e2190fc13d5c to use the
> new busy method are the cause of the behaviour change.
> 
> Signed-off-by: Ben Dooks <ben-linux@...ff.org>
> 
> Index: linux.git/drivers/mmc/host/sdhci.c
> ===================================================================
> --- linux.git.orig/drivers/mmc/host/sdhci.c	2008-11-03 10:01:03.000000000 +0000
> +++ linux.git/drivers/mmc/host/sdhci.c	2008-11-03 12:20:40.000000000 +0000
> @@ -1291,11 +1291,24 @@ static void sdhci_cmd_irq(struct sdhci_h
>  	 *       controllers.
>  	 */
>  	if (host->cmd->flags & MMC_RSP_BUSY) {
> +		u32 present;
> +
>  		if (host->cmd->data)
>  			DBG("Cannot wait for busy signal when also "
>  				"doing a data transfer");
> -		else
> +		else if (!(host->quirks & SDHCI_QUIRK_NO_TCIRQ_ON_NOT_BUSY))
>  			return;

Not the clearest naming I've ever seen. :)
How about NO_BUSY_IRQ?

> +
> +		/* The Samsung SDHCI does not seem to provide an INT_DATA_END
> +		 * when the system goes non-busy, so check the state of the
> +		 * transfer by reading SDHCI_PRESENT_STATE to see if the
> +		 * controller is ready
> +		 */

There is already a note about this being a problem earlier up, so I
don't think we need another.

> +
> +		present = readl(host->ioaddr + SDHCI_PRESENT_STATE);
> +		DBG("busy? present %08x, intstat %08x\n", present, intmask);
> +

And what does this add really? Controllers not being able to wait for
the busy state to end is so common that we can just ignore the problem
here.

> +#define  SDHCI_DATA_BIT(x)	(1 << ((x) + 20))

This was not supposed to be included I suppose :)

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org

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