[RFC][PATCH] plat-mxc: iomux-v3.h: implicitly enable pull-up/down when that's desired

[Baruch Siach]

Hi Paul,

On Mon, Oct 10, 2011 at 11:19:23AM +0400, Paul Fertser wrote:
> To configure pads during the initialisation a set of special constants
> is used, e.g.
> #define MX25_PAD_FEC_MDIO__FEC_MDIO IOMUX_PAD(0x3c4, 0x1cc, 0x10, 0, 0, PAD_CTL_HYS | PAD_CTL_PUS_22K_UP)
> 
> The problem is that no pull-up/down is getting activated unless both
> PAD_CTL_PUE (pull-up enable) and PAD_CTL_PKE (pull/keeper module
> enable) set. This is clearly stated in the i.MX25 datasheet and is
> confirmed by the measurements on hardware. This leads to some rather
> hard to understand bugs such as misdetecting an absent ethernet PHY (a
> real bug i had), unstable data transfer etc. This might affect mx25,
> mx35, mx50, mx51 and mx53 SoCs.
> 
> It's reasonable to expect that if the pullup value is specified, the
> intention was to have it actually active, so we implicitly add the
> needed bits.

IMO, this patch should include the removal of the now redundant PAD_CTL_PKE 
from arch/arm/plat-mxc/include/mach/iomux-mx25.h, and other v3 iomux headers.

baruch

> Cc: stable at kernel.org
> Signed-off-by: Paul Fertser <fercerpav at gmail.com>
> ---
> 
> I'm not sure if that's really suitable for -stable so please excuse me
> if it's not. The issue looks real though and if you prefer fixing it
> any other way, please let me know. Sascha, if you think this's appropriate,
> i'll be happy to send the same fix for barebox.
> 
>  arch/arm/plat-mxc/include/mach/iomux-v3.h |   10 +++++-----
>  1 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm/plat-mxc/include/mach/iomux-v3.h b/arch/arm/plat-mxc/include/mach/iomux-v3.h
> index ebbce33..4509956 100644
> --- a/arch/arm/plat-mxc/include/mach/iomux-v3.h
> +++ b/arch/arm/plat-mxc/include/mach/iomux-v3.h
> @@ -89,11 +89,11 @@ typedef u64 iomux_v3_cfg_t;
>  #define PAD_CTL_HYS			(1 << 8)
>  
>  #define PAD_CTL_PKE			(1 << 7)
> -#define PAD_CTL_PUE			(1 << 6)
> -#define PAD_CTL_PUS_100K_DOWN		(0 << 4)
> -#define PAD_CTL_PUS_47K_UP		(1 << 4)
> -#define PAD_CTL_PUS_100K_UP		(2 << 4)
> -#define PAD_CTL_PUS_22K_UP		(3 << 4)
> +#define PAD_CTL_PUE			(1 << 6 | PAD_CTL_PKE)
> +#define PAD_CTL_PUS_100K_DOWN		(0 << 4 | PAD_CTL_PUE)
> +#define PAD_CTL_PUS_47K_UP		(1 << 4 | PAD_CTL_PUE)
> +#define PAD_CTL_PUS_100K_UP		(2 << 4 | PAD_CTL_PUE)
> +#define PAD_CTL_PUS_22K_UP		(3 << 4 | PAD_CTL_PUE)
>  
>  #define PAD_CTL_ODE			(1 << 3)

-- 
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