Re: [PATCH v6 0/6] Improve PCI memory mapping API

[Damien Le Moal <dlemoal@kernel.org>]

On 10/12/24 20:57, Manivannan Sadhasivam wrote:
> On Sat, Oct 12, 2024 at 08:32:40PM +0900, Damien Le Moal wrote:
>> This series introduces the new functions 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 is defined for inbound ATU entries (e.g.
>> BARs) and is a fixed value, whereas some controllers need a PCI address
>> alignment that depends on the PCI address itself. For instance, the
>> rk3399 SoC controller in endpoint mode 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 .align_addr is
>> introduced and called from the new pci_epc_mem_map() function. This
>> method is optional and for controllers that do not define it, it is
>> assumed that the controller has no PCI address constraint.
>>
>> The functions pci_epc_mem_map() is a helper function which obtains
>> the mapping information, allocates endpoint controller memory according
>> to the mapping size obtained and maps the memory. pci_epc_mem_unmap()
>> unmaps and frees the endpoint memory.
>>
>> This series is organized as follows:
>>  - Patch 1 introduces a small helper to clean up the epc core code
>>  - Patch 2 improves pci_epc_mem_alloc_addr()
>>  - Patch 3 introduce the new align_addr() endpoint controller method
>>    and the epc functions pci_epc_mem_map() and pci_epc_mem_unmap().
>>  - Patch 4 documents these new functions.
>>  - Patch 5 modifies the test endpoint function driver to use 
>>    pci_epc_mem_map() and pci_epc_mem_unmap() to illustrate the use of
>>    these functions.
>>  - Finally, patch 6 implements the RK3588 endpoint controller driver
>>    .align_addr() operation to satisfy that controller PCI address
>>    alignment constraint.
>>
>> This patch series was tested using the pci endpoint test driver (as-is
>> and a modified version removing memory allocation alignment on the host
>> side) as well as with a prototype NVMe endpoint function driver (where
>> data transfers use addresses that are never aligned to any specific
>> boundary).
>>
> 
> Applied to pci/endpoint!

Awesome ! Thanks a lot !

-- 
Damien Le Moal
Western Digital Research