Re: [RFC PATCH] wl12xx: Change claiming of the (SDIO) bus

[Juuso Oikarinen <juuso.oikarinen@nokia.com>]

On Fri, 2011-02-04 at 13:35 +0200, ext juuso.oikarinen@nokia.com wrote:
> From: Juuso Oikarinen <juuso.oikarinen@nokia.com>
> 
> Currently, the SDIO bus is claimed separately for each and every SDIO
> transaction - i.e. every register write/read etc.
> 
> The SDIO claiming is a relatively heavy operation. In a worst case scenario,
> it will put the SDIO bus on suspend, stop relevant clocks etc which all can be
> extremely costly if done between each SDIO transaction. This has a dramatic
> impact on the maximum throughput achieved.
> 
> The driver already manages its access to the bus as it needs to manage
> chipset ELP. This mechanism disables ELP for the duration of the whole bus
> access, consisting of multiple transactions.
> 
> Into the IO layer, this patch implements a claim/unclaim function, which is
> used to claim access to the bus. Relevant functions are checked and updated to
> maintain correctly the claim reference counter, so that each claim is paired
> with a corresponding unclaim.
> 
> For PLT and ad-hoc modes the bus is kept claimed contantly.
> 
> For AP mode, this patch brings no change to the previous way of working,
> someone familiar with it and with the ability to test it may implement
> something similar as is done here for the other modes.
> 
> For the SPI bus, the claim/unclaim functions are not implemented, i.e. no
> change to functionality.
> 
> Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
> ---

I realised there are two separate issues here in one patch. I'll need to
split this into two patches. Also, there are some other issues I need to
address.

-Juuso