Messages in this thread | | | Subject | Re: [PATCH RFC 0/2] Add Renesas RPC-IF support | From | Sergei Shtylyov <> | Date | Wed, 11 Dec 2019 19:08:51 +0300 |
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HEllo
On 12/11/2019 05:33 PM, Chris Brandt wrote:
>> Here's a set of 2 patches against Linus' repo. Renesas Reduced Pin Count >> Interface (RPC-IF) allows a SPI flash or HyperFlash connected to the SoC to >> be accessed via the external address space read mode or the manual mode. > > Looking at this driver, all it is are APIs. Meaning another driver is > needed to sit in between the MTD layer and this HW driver layer.
Between the hardware and SPI, and between the hardware and HyperFlash infrastructure. There's a lot of the common hardware code common between these 2 driver areas.
> In the driver that I did, if the "RPC" HW is going to be used to control > a SPI Flash device, it registered a spi controller and then the MTD > layer could access the device just like any other SPI controller driver. No > additional drivers are needed.
We're already been thru that with Mason's patch -- I don't want the code duplicated between 2 drivers.
> Looking at the hyperbus driver that is in drivers/mtd/hyperbus/, it > seems that if the "RPC" HW is going to be used to control HyperFlash, then
Sure. But the code controlling RPC hardware is largely the same b/w 2 cases.
> all you would need to do is register a hyperbus controller using > hyperbus_register_device(). Then the MTD layer could read/write the flash using > normal MTD CFI interface.
That's what I do (the current realization makes too many assumptions about the HF hardware (both direct read and write).
> Why do you think you need another layer in between the HW driver and the > MTD layer?
Because we don't want any duplicated code. Also, think about DT -- it describes the hardware, not the driver configuration.
> Is your goal to make a multi-layered system where the HW jumps back and forth > in between operating modes at runtime? I'm not sure of the use case for all of > this.
My goal is to prevent the code duplication (and keep DT sane too).
> Chris
MBR, Sergei
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