linux-kernel - Re: [PATCH] spi: spi-davinci: deassert CS on setup()

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

Date:	Tue, 10 Sep 2013 19:44:11 -0700
From:	Trent Piepho <tpiepho@...il.com>
To:	Ben Gardiner <ben.l.gardiner@...il.com>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	"spi-devel-general@...ts.sourceforge.net" 
	<spi-devel-general@...ts.sourceforge.net>,
	davinci-linux-open-source@...ux.davincidsp.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: spi-davinci: deassert CS on setup()

It is supposed to be possible to call setup() on one slave while
transfers on another slave attached to the same master are in
progress.

A cursory look at the code makes it seem that all the CS control bits
share SPIDAT1?  Will writing to SPIDAT1 in davinci_spi_chipselect()
cause a race if another chipselect is being used?

On Tue, Sep 10, 2013 at 10:10 AM, Ben Gardiner <ben.l.gardiner@...il.com> wrote:
> The mmc_spi driver's mmc_cs_off() function states that "chipselect will always
> be inactive after setup()"; however, the spi-davinci driver's setup() leaves CS
> state unchanged.
>
> Add a call to davinci_spi_chipselect(spi, BITBANG_CS_INACTIVE) to the spi-
> davinci drivers' setup() function.
>
> Signed-off-by: Ben Gardiner <ben.l.gardiner@...il.com>
> ---
>  drivers/spi/spi-davinci.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
> index 707966b..f0f4dbd 100644
> --- a/drivers/spi/spi-davinci.c
> +++ b/drivers/spi/spi-davinci.c
> @@ -404,6 +404,7 @@ static int davinci_spi_setup(struct spi_device *spi)
>                     (pdata->chip_sel[spi->chip_select] == SPI_INTERN_CS))
>                         set_io_bits(dspi->base + SPIPC0, 1 << spi->chip_select);
>
> +               davinci_spi_chipselect(spi, BITBANG_CS_INACTIVE);
>         }
>
>         if (spi->mode & SPI_READY)
> --
> 1.8.1.2
>
>
> ------------------------------------------------------------------------------
> How ServiceNow helps IT people transform IT departments:
> 1. Consolidate legacy IT systems to a single system of record for IT
> 2. Standardize and globalize service processes across IT
> 3. Implement zero-touch automation to replace manual, redundant tasks
> http://pubads.g.doubleclick.net/gampad/clk?id=51271111&iu=/4140/ostg.clktrk
> _______________________________________________
> spi-devel-general mailing list
> spi-devel-general@...ts.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/spi-devel-general
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/