Re: [PATCH v2 00/18] Improve PCI memory mapping API

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Apr 03, 2024 at 04:58:42PM +0900, Damien Le Moal wrote:
> On 4/3/24 16:50, Manivannan Sadhasivam wrote:
> > On Sat, Mar 30, 2024 at 01:19:10PM +0900, Damien Le Moal wrote:
> >> This series introduces the new functions pci_epc_map_align(),
> >> pci_epc_mem_map() and pci_epc_mem_unmap() to improve handling of the
> >> PCI address mapping alignment constraints of endpoint controllers in a
> >> controller independent manner.
> >>
> >> The issue fixed is that the fixed alignment defined by the "align" field
> >> of struct pci_epc_features assumes that the alignment of the endpoint
> >> memory used to map a RC PCI address range is independent of the PCI
> >> address being mapped. But that is not the case for the rk3399 SoC
> >> controller: in endpoint mode, this controller uses the lower bits of the
> >> local endpoint memory address as the lower bits for the PCI addresses
> >> for data transfers. That is, when mapping local memory, one must take
> >> into account the number of bits of the RC PCI address that change from
> >> the start address of the mapping.
> >>
> >> To fix this, the new endpoint controller method .map_align is introduced
> >> and called from pci_epc_map_align(). This method is optional and for
> >> controllers that do not define it, the mapping information returned
> >> is based of the fixed alignment constraint as defined by the align
> >> feature.
> >>
> >> The functions pci_epc_mem_map() is a helper function which obtains
> >> mapping information, allocates endpoint controller memory according to
> >> the mapping size obtained and maps the memory. pci_epc_mem_map() unmaps
> >> and frees the endpoint memory.
> >>
> >> This series is organized as follows:
> >>  - Patch 1 tidy up the epc core code
> >>  - Patch 2 and 3 introduce the new map_align endpoint controller method
> >>    and related epc functions.
> >>  - Patch 4 to 6 modify the test endpoint driver to use these new
> >>    functions and improve the code of this driver.
> > 
> > While posting the next version, please split the endpoint patches into a
> > separate series. It helps in code review and can be applied separately.
> 
> Which patches ? They are all endpoint related:
>  (1) Core code
>  (2) test function driver

Till patch 6, that's why I inlined my reply at the 3rd point.

>  (3) rockchip rk3399 controller
> 
> (2) and (3) depend on the patches in (1), so splitting the series is a big
> possible only if (1) is applied first, so that is a source of delays and breaks
> the context of the patches...
> 

If you split patches 1-6 and post the rest of the Rockchip patches as a follow
up, it perfectly makes sense.

- Mani

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