On Fri, May 10, 2013 at 08:10:18PM +0400, Igor Mitsyanko wrote: > This is an initial attempt to change our SD card model to use asynchronious > input/output API instead of synchronious one. This will require converting of > every user also. Right now I've converted only PL181 model, and I'll wait > for some feedback on taken approach before I'll continue with other users. > > New async SD interface is built on two callbacks: > 1 Callback which models arrival of start bit on DAT line from card (start bit) > 2 Callback modeling deasserting of DAT0 line by card when it has finished > programming data (data busy end) > > This is based on SD card specification. > Start bit is issued for every new block of data coming from card. > DAT0 line is kept low by card to signal busy state, while data block is being > programmed by card and it can't receive new data. > > Furthermore, I decided to drop data buffering on SD controller side. We > already > have two buffers in SD card model, no need to have another one in controller > model. > We can avoid intermediate copying from card's buffer to controller's buffer, > and > read/write directly from card. > > Tested by running this Fedora image > https://fedoraproject.org/wiki/Architectures/ARM/F18/Versatile_Express > on versatile board. > > Igor Mitsyanko (7): > sd.c: introduce AIO related members in SD state > sd.c: introduce variable for trekking valid data > sd.c: introduce "start bit" and "busy deasserted" callbacks > sd.c: use callbacks as a flag to use async IO > sd.c: introduce async read operation > sd.c: introduce async write interface > pl181.c: convert to async IO SD card interface > > hw/sd/omap_mmc.c | 6 +- > hw/sd/pl181.c | 302 > +++++++++++++++++++++++++++++++++------------------- > hw/sd/pxa2xx_mmci.c | 2 +- > hw/sd/sd.c | 272 ++++++++++++++++++++++++++++++++++++++++++---- > hw/sd/sdhci.c | 4 +- > include/hw/sd.h | 3 +- > 6 files changed, 449 insertions(+), 140 deletions(-)
Thanks for doing this! It makes me happy when we replace synchronous block layer callers with asynchronous ones. I didn't review each line but overall it seems like the right direction. Stefan
