Re: [PATCH v3 07/12] PCI: rockchip-ep: Refactor rockchip_pcie_ep_probe() MSI-X hiding

Damien Le Moal
2024-10-10T08:38:04Z

On 2024/10/10 17:09, Manivannan Sadhasivam wrote:
> On Thu, Oct 10, 2024 at 12:55:12PM +0530, Manivannan Sadhasivam wrote:
>> On Mon, Oct 07, 2024 at 01:12:13PM +0900, Damien Le Moal wrote:
>>> Move the code in rockchip_pcie_ep_probe() to hide the MSI-X capability
>>> to its own function, rockchip_pcie_ep_hide_msix_cap(). No functional
>>> changes.
>>>
>>> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
>>
>> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
>>
>> Btw, can someone from Rockchip confirm if this hiding is necessary for all the
>> SoCs? It looks to me like an SoC quirk.
>>
>> - Mani
>>
>>> ---
>>> drivers/pci/controller/pcie-rockchip-ep.c | 54 +++++++++++++----------
>>> 1 file changed, 30 insertions(+), 24 deletions(-)
>>>
>>> diff --git a/drivers/pci/controller/pcie-rockchip-ep.c b/drivers/pci/controller/pcie-rockchip-ep.c
>>> index 523e9cdfd241..7a1798fcc2ad 100644
>>> --- a/drivers/pci/controller/pcie-rockchip-ep.c
>>> +++ b/drivers/pci/controller/pcie-rockchip-ep.c
>>> @@ -581,6 +581,34 @@ static void rockchip_pcie_ep_release_resources(struct rockchip_pcie_ep *ep)
>>> pci_epc_mem_exit(ep->epc);
>>> }
>>>
>>> +static void rockchip_pcie_ep_hide_msix_cap(struct rockchip_pcie *rockchip)
>
> Perhaps a better name would be rockchip_pcie_disable_broken_msix()? As the
> function essentially disables MSIx which is broken. Again, it'd be good to know
> if this applies to all SoCs or just a few.

This is for the rk3399... I am not aware of multiple versions of that SoC.
The pcie_rockchip driver is for that SoC only as far as I know. This is unlike
the Designware IP block which is used in multiple SoCs.

>
> - Mani
>
>>> +{
>>> + u32 cfg_msi, cfg_msix_cp;
>>> +
>>> + /*
>>> + * MSI-X is not supported but the controller still advertises the MSI-X
>>> + * capability by default, which can lead to the Root Complex side
>>> + * allocating MSI-X vectors which cannot be used. Avoid this by skipping
>>> + * the MSI-X capability entry in the PCIe capabilities linked-list: get
>>> + * the next pointer from the MSI-X entry and set that in the MSI
>>> + * capability entry (which is the previous entry). This way the MSI-X
>>> + * entry is skipped (left out of the linked-list) and not advertised.
>>> + */
>>> + cfg_msi = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
>>> + ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
>>> +
>>> + cfg_msi &= ~ROCKCHIP_PCIE_EP_MSI_CP1_MASK;
>>> +
>>> + cfg_msix_cp = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
>>> + ROCKCHIP_PCIE_EP_MSIX_CAP_REG) &
>>> + ROCKCHIP_PCIE_EP_MSIX_CAP_CP_MASK;
>>> +
>>> + cfg_msi |= cfg_msix_cp;
>>> +
>>> + rockchip_pcie_write(rockchip, cfg_msi,
>>> + PCIE_EP_CONFIG_BASE + ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
>>> +}
>>> +
>>> static int rockchip_pcie_ep_probe(struct platform_device *pdev)
>>> {
>>> struct device *dev = &pdev->dev;
>>> @@ -588,7 +616,6 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
>>> struct rockchip_pcie *rockchip;
>>> struct pci_epc *epc;
>>> int err;
>>> - u32 cfg_msi, cfg_msix_cp;
>>>
>>> ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
>>> if (!ep)
>>> @@ -619,6 +646,8 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
>>> if (err)
>>> goto err_disable_clocks;
>>>
>>> + rockchip_pcie_ep_hide_msix_cap(rockchip);
>>> +
>>> /* Establish the link automatically */
>>> rockchip_pcie_write(rockchip, PCIE_CLIENT_LINK_TRAIN_ENABLE,
>>> PCIE_CLIENT_CONFIG);
>>> @@ -626,29 +655,6 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
>>> /* Only enable function 0 by default */
>>> rockchip_pcie_write(rockchip, BIT(0), PCIE_CORE_PHY_FUNC_CFG);
>>>
>>> - /*
>>> - * MSI-X is not supported but the controller still advertises the MSI-X
>>> - * capability by default, which can lead to the Root Complex side
>>> - * allocating MSI-X vectors which cannot be used. Avoid this by skipping
>>> - * the MSI-X capability entry in the PCIe capabilities linked-list: get
>>> - * the next pointer from the MSI-X entry and set that in the MSI
>>> - * capability entry (which is the previous entry). This way the MSI-X
>>> - * entry is skipped (left out of the linked-list) and not advertised.
>>> - */
>>> - cfg_msi = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
>>> - ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
>>> -
>>> - cfg_msi &= ~ROCKCHIP_PCIE_EP_MSI_CP1_MASK;
>>> -
>>> - cfg_msix_cp = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
>>> - ROCKCHIP_PCIE_EP_MSIX_CAP_REG) &
>>> - ROCKCHIP_PCIE_EP_MSIX_CAP_CP_MASK;
>>> -
>>> - cfg_msi |= cfg_msix_cp;
>>> -
>>> - rockchip_pcie_write(rockchip, cfg_msi,
>>> - PCIE_EP_CONFIG_BASE + ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
>>> -
>>> rockchip_pcie_write(rockchip, PCIE_CLIENT_CONF_ENABLE,
>>> PCIE_CLIENT_CONFIG);
>>>
>>> --
>>> 2.46.2
>>>
>>
>> --
>> மணிவண்ணன் சதாசிவம்
>

--
Damien Le Moal
Western Digital Research