Hi Jagan, On 10 August 2014 03:16, Jagan Teki <jagannadh.t...@gmail.com> wrote: > On Sun, Aug 10, 2014 at 2:59 AM, Simon Glass <s...@chromium.org> wrote: >> Hi, >> >> On 14 July 2014 18:56, Simon Glass <s...@chromium.org> wrote: >>> Up until now driver model has not been used for any type of bus. Buses >>> have some unique properties and needs, so we cannot claim that driver >>> model can cover all the common cases unless we have converted a bus over >>> to driver model. >>> >>> SPI is a reasonable choice for this next step. It has a fairly simple >>> API and not too many dependencies. The main one is SPI flash so we may >>> as well convert that also. Since the boards I test with have cros_ec I >>> have also included that, for SPI only. >>> >>> The technique used is make use of driver model's supported data structures >>> to hold information currently kept by each subsystem in a private data >>> structure. Since 'struct spi_slave' relates to the slave device on the bus >>> it is stored in the 'parent' data with each child device of the bus. >>> Since 'struct spi_flash' is a standard interface used for each SPI flash >>> driver, it is stored in the SPI FLash uclass's private data for each >>> device. >>> >>> New defines are created to enable driver model for each subsystem. These >>> are: >>> >>> CONFIG_DM_SPI >>> CONFIG_DM_SPI_FLASH >>> CONFIG_DM_CROS_EC >>> >>> This allows us to move some boards and drivers to driver model, while >>> leaving others behind. A 'big bang' conversion of everything to driver >>> model, event at a subsystem level, is never going to work. >>> >>> On the other hand, we change the driver at the same time as the CONFIG >>> option is enabled. Keeping both version of the driver around involves a >>> flock of #ifdefs, the benefit of which is not apparent to me, since the >>> old code is removed anyway. >>> >>> There is some cost in changing the uclass interface after it is created, >>> so if you have limited time, please spend it reviewing the uclass >>> interfaces in spi.h and spi_flash.h. These need to be supported by each >>> driver, so changing them later may involve changing multiple drivers. >>> >>> To help with conversion of SPI drivers to driver model, documentation is >>> provided which takes the happy camper through the process with an example. >>> >>> As always, driver model patches are available at u-boot-dm.git branch >>> 'working'. >>> >>> Note: This series is not fully ready - e.g. some header files are missing >>> comments. But I wanted to get it out for review early since some SPI work >>> is ongoing which might depend on it. >> >> Are there any comments on this series please? I'd like to apply these >> to dm/master early next week, excluding the exynos ones. > > I will be busy in next full week, give me 2 more weeks. > Probably I will give my comments on next to next weekend.
I'll see what I can do. It has been out for review for 4 weeks :-) Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
