Re: [PATCH] sdio: add CD disable support

[David Vrabel]

Ohad Ben-Cohen wrote:
> From: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
> 
> To save power, the pull-up resistor on CD/DAT[3] (pin 1)
> of the card can be disconnected. This is desired, e.g.,
> with embedded SDIO devices which do not rely on this pin
> for card detection.

Platforms may rely on the card's pull-up and not fit/configure an
external one.  There may need to be a way for host controller drivers to
 say this and prevent the disabling of the card's DAT3 pull-up.

> Signed-off-by: Ohad Ben-Cohen  <ohad@xxxxxxxxxx>
> ---
>  drivers/mmc/core/sdio.c  |   32 ++++++++++++++++++++++++++++++++
>  include/linux/mmc/card.h |    3 ++-
>  2 files changed, 34 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
> index fb99ccf..4c4c9a9 100644
> --- a/drivers/mmc/core/sdio.c
> +++ b/drivers/mmc/core/sdio.c
> @@ -165,6 +165,31 @@ static int sdio_enable_wide(struct mmc_card *card)
>  }
>  
>  /*
> + * Disconnect the pull-up resistor on CD/DAT[3] if requested by the card.
> + * If card detection is not needed, this can save some power.
> + */

The first sentence of this comment doesn't make sense.  The decision to
disable the pull-up is for the controller driver to make, not that card.

David
-- 
David Vrabel, Senior Software Engineer, Drivers
CSR, Churchill House, Cambridge Business Park,  Tel: +44 (0)1223 692562
Cowley Road, Cambridge, CB4 0WZ                 http://www.csr.com/


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