[U-Boot] [PATCH v3 0/29] Introduce driver model support for SPI, SPI flash, cros_ec

[Jagan Teki]

Hi Simon,

On 10 October 2014 07:36, Simon Glass <sjg at chromium.org> wrote:
> Hi Jagan,
>
> On 9 October 2014 04:33, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>> On 9 October 2014 02:03, Simon Glass <sjg at chromium.org> wrote:
>>> Hi,
>>>
>>> On 29 September 2014 13:34, Simon Glass <sjg at 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, even at a subsystem level, is never going to work.
>>>>
>>>> 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 assist with the conversion of other SPI drivers, a README file is
>>>> added to walk through the process.
>>>>
>>>> So far, sandbox, exynos and tegra drivers are converted over.
>>>>
>>>> As always, driver model patches are available at u-boot-dm.git branch
>>>> 'working'. There is a branch for just this series called 'spi-working'.
>>>
>>> I think this has had enough time out there. So I will push this to
>>> dm/next later this week.
>>
>> Sorry - I need to review a lot wrt v3.
>> I do understand that it has been in enough time, but this causes a
>> significant changes on
>> entire framework, please hold on for a while I need to think with
>> respect on qspi stuff with in
>> the spi framework.
>
> Well I'm not sure it supports setting of the flags that are needed for
> that. I don't have a platform to test with anyway.
>
> On the other hand adding that support to driver model could easily be
> a separate effort. I don't see a good reason to hold up the core SPI /
> SPI flash support.

Partially agreed at this moment, let me think and review the whole stuff.
I would place all these stuff on to my master-next, once I'm OK.

Any changes based on my strategy wrt qspi stuff - I may change these.
But I will push all these later on the 13/10 release.

Comments?

thanks!
-- 
Jagan.