Re: [PATCH v5 0/9] PCI: Enable Power and configure the TC9563 PCIe switch

[Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>]

On 4/19/2025 1:30 AM, Bjorn Helgaas wrote:
> On Sat, Apr 12, 2025 at 07:19:49AM +0530, Krishna Chaitanya Chundru wrote:
>> TC9563 is the PCIe switch which has one upstream and three downstream
>> ports. To one of the downstream ports ethernet MAC is connected as endpoint
>> device. Other two downstream ports are supposed to connect to external
>> device. One Host can connect to TC956x by upstream port.
> 
> I guess this topology is for one specific platform that includes the
> TC9563?  Since it's a PCIe switch, I assume it could also be used in
> other platforms with other topologies?
> 
This topology is for the switch not for per platform, the switch exposes
two DSP's for external device and one DSP has always integrated MAC.
>> TC9563 switch power is controlled by the GPIO's. After powering on
>> the switch will immediately participate in the link training. if the
>> host is also ready by that time PCIe link will established.
>>
>> The TC9563 needs to configured certain parameters like de-emphasis,
>> disable unused port etc before link is established.
>>
>> As the controller starts link training before the probe of pwrctl driver,
>> the PCIe link may come up as soon as we power on the switch. Due to this
>> configuring the switch itself through i2c will not have any effect as
>> this configuration needs to done before link training. To avoid this
>> introduce two functions in pci_ops to start_link() & stop_link() which
>> will disable the link training if the PCIe link is not up yet.
>>
>> This series depends on the https://lore.kernel.org/all/20250124101038.3871768-3-krishna.chundru@oss.qualcomm.com/
> 
> How so?
> https://lore.kernel.org/all/20250124101038.3871768-3-krishna.chundru@oss.qualcomm.com/
> adds a schema "n-fts" property, but this series doesn't mention
> "n-fts".  This series *does* add this:
> 
>    of_property_read_u8_array(node, "nfts", cfg->nfts, 2);
> 
> Is that supposed to be the same thing, or does "nfts" magically match
> "n-fts"?
>
It is miss from my side, thanks for pointing out, I will
fix this in next patch series.

- Krishna Chaitanya.

> Bjorn