Re: [RFC v1 1/1] Refactor ACPI DMA to support platforms without shared info descriptor in CSRT

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Mar 22, 2023 at 07:56:11AM +0000, Niyas Sait wrote:
> On 21/03/2023 17:53, Andy Shevchenko wrote:
> 
> > can_we_avoid_long_name_of_the_functions_please() ?
> 
> Sure, will do that.
> 
> > Also is this renaming is a must?
> 
> It is not a must. I considered the existing method with shared info
> as a special case as it uses non standard descriptors from CSRT table
> and introduced the new function to handle it.
> 
> > Btw, what is the real argument of not using this table?
> > 
> > Yes, I know that this is an MS extension, but why ARM needs something else and
> > why even that is needed at all? CSRT is only for the _shared_ DMA resources
> > and I think most of the IPs nowadays are using private DMA engines (or
> > semi-private when driver based on ID can know which channel services which
> > device).
> 
> The issue is that shared info descriptor is not part of CSRT definition [1]
> and I think it is not standardized or documented anywhere.
> 
> I was specifically looking at NXP I.MX8MP platform and the DMA lines for
> devices are specified using FixedDMA resource descriptor. I think other Arm
> platforms like RPi have similar requirement.

Perhaps, but my question is _why_ is it so?
I.o.w. what is the technical background for this solution.

> [1] https://uefi.org/sites/default/files/resources/CSRT%20v2.pdf

-- 
With Best Regards,
Andy Shevchenko





[Index of Archives]     [Linux Kernel]     [Linux ARM (vger)]     [Linux ARM MSM]     [Linux Omap]     [Linux Arm]     [Linux Tegra]     [Fedora ARM]     [Linux for Samsung SOC]     [eCos]     [Linux PCI]     [Linux Fastboot]     [Gcc Help]     [Git]     [DCCP]     [IETF Announce]     [Security]     [Linux MIPS]     [Yosemite Campsites]

  Powered by Linux