linux-kernel - Re: [PATCH 08/11] spi-dw: Ensure fifo lenght is set.

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Message-ID: <BANLkTi=Jv2aVuHqVXh77aGxMFV_Q_wXQCg@mail.gmail.com>
Date:	Wed, 22 Jun 2011 21:55:22 -0600
From:	Grant Likely <grant.likely@...retlab.ca>
To:	dirk.brandewie@...il.com
Cc:	linux-kernel@...r.kernel.org,
	spi-devel-general@...ts.sourceforge.net
Subject: Re: [PATCH 08/11] spi-dw: Ensure fifo lenght is set.

On Wed, Jun 22, 2011 at 8:00 PM,  <dirk.brandewie@...il.com> wrote:
> From: Dirk Brandewie <dirk.brandewie@...il.com>
>
> Bug on fifo_len not being set.  The fifo sizing routine does not work
> since the txfltr register can not be written while the controller is
> enabled. The max value of txfltr can be larger than the fifo.  The
> register allows values upto 0x3f (63) the fifo depth on the Intel
> SOC's if 40
>
> Signed-off-by: Dirk Brandewie <dirk.brandewie@...il.com>
> ---
>  drivers/spi/spi-dw.c |   18 ++----------------
>  1 files changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> index ad92826..cc38aa0 100644
> --- a/drivers/spi/spi-dw.c
> +++ b/drivers/spi/spi-dw.c
> @@ -776,25 +776,11 @@ static int destroy_queue(struct spi_dw *dws)
>  /* Restart the controller, disable all interrupts, clean rx fifo */
>  static void spi_dw_hw_init(struct spi_dw *dws)
>  {
> +       BUG_ON(!dws->fifo_len);
> +

Ditto here.  BUG is too big a reaction.  Fail to initialize the
device, sure, and print a warning, but don't BUG.

g.

>        spi_dw_disable(dws);
>        spi_dw_mask_intr(dws, 0xff);
>        spi_dw_enable(dws);
> -
> -       /*
> -        * Try to detect the FIFO depth if not set by interface driver,
> -        * the depth could be from 2 to 256 from HW spec
> -        */
> -       if (!dws->fifo_len) {
> -               u32 fifo;
> -               for (fifo = 2; fifo <= 257; fifo++) {
> -                       dw_writew(dws, txfltr, fifo);
> -                       if (fifo != dw_readw(dws, txfltr))
> -                               break;
> -               }
> -
> -               dws->fifo_len = (fifo == 257) ? 0 : fifo;
> -               dw_writew(dws, txfltr, 0);
> -       }
>  }
>
>  int __devinit spi_dw_add_host(struct spi_dw *dws)
> --
> 1.7.3.4
>
>
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>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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