Re: [PATCH] OMAP3 : Fix McSPI RX Timeout

[Tony Lindgren <tony@atomide.com>]

* manjugk@ti.com <manjugk@ti.com> [091005 23:42]:
> McSPI RX timeout issues are reported on some of the OMAP3 custom boards.
> 
> After verifying configuration sequence in TRM, there seems to be issue with 
> McSPI configuration sequence.
> 
> The steps to be followed for both TX and RX:
> 1. Configure OMAP2_MCSPI_CHCONF0 register with required settings such as
> TX/RX mode, word length, force chip select(if required).
> 2. Set MS bit to 0 in OMAP2_MCSPI_CHCTRL0 register to provide the clock.
> 3. Enable SPI channel in OMAP2_MCSPI_MODULCTRL
> 
> But, the sequence used in current code seems to be wrong. Here it is:
> 1. Set MS bit to 0 in OMAP2_MCSPI_CHCTRL0 register to provide the clock
> (This is done during bootup)
> 2. Enable SPI channel in OMAP2_MCSPI_MODULCTRL
> 3. Configure OMAP2_MCSPI_CHCONF0 register with required settings such as
> TX/RX mode, word length, force chip select(if required).
> 
> After correcting configuration sequence, the timeout seems to be not
> reproducible anymore.

Please resend this to the right lists one for merging:

$ grep -A7 "SPI SUBSYSTEM" MAINTAINERS 
SPI SUBSYSTEM
M:      David Brownell <dbrownell@users.sourceforge.net>
L:      spi-devel-general@lists.sourceforge.net
S:      Maintained
F:      Documentation/spi/
F:      drivers/spi/
F:      include/linux/spi/

Please also Cc linux-omap list too so people can easily keep track of it.

Regards,

Tony


> 
> Signed-off-by: Manjunatha GK <manjugk@ti.com>
> ---
>  drivers/spi/omap2_mcspi.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
> index ba1a872..846485c 100644
> --- a/drivers/spi/omap2_mcspi.c
> +++ b/drivers/spi/omap2_mcspi.c
> @@ -802,7 +802,6 @@ static void omap2_mcspi_work(struct work_struct *work)
>  		spi = m->spi;
>  		cs = spi->controller_state;
>  
> -		omap2_mcspi_set_enable(spi, 1);
>  		list_for_each_entry(t, &m->transfers, transfer_list) {
>  			if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
>  				status = -EINVAL;
> @@ -830,6 +829,9 @@ static void omap2_mcspi_work(struct work_struct *work)
>  				chconf |= OMAP2_MCSPI_CHCONF_TRM_TX_ONLY;
>  			mcspi_write_chconf0(spi, chconf);
>  
> +			omap2_mcspi_set_master_mode(mcspi->master);
> +
> +			omap2_mcspi_set_enable(spi, 1);
>  			if (t->len) {
>  				unsigned	count;
>  
> -- 
> 1.6.0.4
> 
> --
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