Re: [PATCH V2] firmware: arm_scmi: Make scmi core independent of transport type

On Tue, Jan 14, 2020 at 10:26 AM Viresh Kumar [off-list ref] wrote:

On 13-01-20, 12:36, Arnd Bergmann wrote:

quoted

On Mon, Jan 13, 2020 at 7:42 AM Viresh Kumar [off-list ref] wrote:

To answer all three, what I meant is that the payload pointer appears
to be transport specific and

I am not sure if I understood the below statement properly. Is there
something missing from it ?

quoted

should not be part of the common
structure if there is generic way to access it.

The scmi protocol requires a block of shared memory which is
represented by struct scmi_shared_mem, and payload is this memory
block itself. This block of memory is accessed throughout driver.c
file using ioread/write commands. If payload is transport specific, so
will be those accesses, isn't it ? Are you suggesting to move all this
to mailbox.c (the transport specific file) instead ? I am sorry, but I
am not able to understand how exactly you want me to reorder code here
:(

My point was that you cannot mix __iomem accesses with pointer
accesses. As I understood it, the current version uses a pointer to a
hardware mailbox with structured data, so you have to use ioremap()
to get a token you can pass into ioread(), but (some of) the new
transport types would just be backed by regular RAM, on which this
is not a well-defined operation and you have to use memremap()
and memcpy() instead.

     Arnd

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