-trimmed cc-list
On 2 July 2018 at 09:57, <honghui.zhang@xxxxxxxxxxxx> wrote:
> From: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>
>
> The MTCMOS of PCIe Host for MT2712 and MT7622 will be off when system
> suspend, and all the internal control register will be reset after system
> resume. The PCIe link should be re-established and the related control
> register values should be re-set after system resume.
Sounds very familiar as what is implemented in
drivers/mmc/host/sdhci-xenon.c. Please have a look, possibly you can
get inspired to use the similar pattern.
A few comments below. However, please note, I am not an expert in PCIe
so I may overlook some obvious things. I am relying on Lorenzo or some
other PCIe expert, to fill in.
>
> Signed-off-by: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>
> Acked-by: Ryder Lee <ryder.lee@xxxxxxxxxxxx>
> ---
> drivers/pci/controller/pcie-mediatek.c | 67 ++++++++++++++++++++++++++++++++++
> 1 file changed, 67 insertions(+)
>
> diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
> index 86918d4..175d7b6 100644
> --- a/drivers/pci/controller/pcie-mediatek.c
> +++ b/drivers/pci/controller/pcie-mediatek.c
> @@ -134,12 +134,14 @@ struct mtk_pcie_port;
> /**
> * struct mtk_pcie_soc - differentiate between host generations
> * @need_fix_class_id: whether this host's class ID needed to be fixed or not
> + * @pm_support: whether the host's MTCMOS will be off when suspend
> * @ops: pointer to configuration access functions
> * @startup: pointer to controller setting functions
> * @setup_irq: pointer to initialize IRQ functions
> */
> struct mtk_pcie_soc {
> bool need_fix_class_id;
> + bool pm_support;
> struct pci_ops *ops;
> int (*startup)(struct mtk_pcie_port *port);
> int (*setup_irq)(struct mtk_pcie_port *port, struct device_node *node);
> @@ -1197,12 +1199,75 @@ static int mtk_pcie_probe(struct platform_device *pdev)
> return err;
> }
>
> +static int __maybe_unused mtk_pcie_suspend_noirq(struct device *dev)
I am not sure I understand why you need to suspend the device in the
"noirq" phase. Isn't it fine to do that in the regular suspend phase?
> +{
> + struct mtk_pcie *pcie = dev_get_drvdata(dev);
> + const struct mtk_pcie_soc *soc = pcie->soc;
> + struct mtk_pcie_port *port;
> +
> + if (!soc->pm_support)
> + return 0;
> +
> + if (list_empty(&pcie->ports))
> + return 0;
> +
> + list_for_each_entry(port, &pcie->ports, list) {
> + clk_disable_unprepare(port->pipe_ck);
> + clk_disable_unprepare(port->obff_ck);
> + clk_disable_unprepare(port->axi_ck);
> + clk_disable_unprepare(port->aux_ck);
> + clk_disable_unprepare(port->ahb_ck);
> + clk_disable_unprepare(port->sys_ck);
> + phy_power_off(port->phy);
> + phy_exit(port->phy);
> + }
> +
> + mtk_pcie_subsys_powerdown(pcie);
Why not gate clocks, unconditionally not depending on if pm_support is
set or not, during system suspend?
I understand that you for some SoCs needs also to restore registers
during system resume, but that's a different thing, isn't it?
> +
> + return 0;
> +}
> +
> +static int __maybe_unused mtk_pcie_resume_noirq(struct device *dev)
> +{
> + struct mtk_pcie *pcie = dev_get_drvdata(dev);
> + const struct mtk_pcie_soc *soc = pcie->soc;
> + struct mtk_pcie_port *port, *tmp;
> +
> + if (!soc->pm_support)
> + return 0;
> +
> + if (list_empty(&pcie->ports))
> + return 0;
> +
> + if (dev->pm_domain) {
> + pm_runtime_enable(dev);
> + pm_runtime_get_sync(dev);
I noticed, Lorenzo wanted me to comment on this, so here it goes.
I guess the reason to why you make these pm_runtime_*() calls, is
because you want to restore the actions taken during
mtk_pcie_suspend_noirq() (which calls mtk_pcie_subsys_powerdown ->
pm_runtime_disable|put*())?
If that's the case, I would rather avoid calling pm_runtime_disable()
and pm_runtime_put() via mtk_pcie_suspend_noirq(), simply because it
isn't needed.
Of course, another option is to follow the pattern in
drivers/mmc/host/sdhci-xenon.c.
Overall, I am also wondering why only runtime PM is used when there is
a PM domain attached to the device? That seems to make the logic in
the driver, unnecessary complicated. Why not use runtime
unconditionally and thus enable it during ->probe()?
> + }
> +
> + clk_prepare_enable(pcie->free_ck);
> +
> + list_for_each_entry_safe(port, tmp, &pcie->ports, list)
> + mtk_pcie_enable_port(port);
> +
> + /* In case of EP was removed while system suspend. */
> + if (list_empty(&pcie->ports))
> + mtk_pcie_subsys_powerdown(pcie);
> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops mtk_pcie_pm_ops = {
> + SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(mtk_pcie_suspend_noirq,
> + mtk_pcie_resume_noirq)
> +};
> +
> static const struct mtk_pcie_soc mtk_pcie_soc_v1 = {
> .ops = &mtk_pcie_ops,
> .startup = mtk_pcie_startup_port,
> };
>
> static const struct mtk_pcie_soc mtk_pcie_soc_mt2712 = {
> + .pm_support = true,
> .ops = &mtk_pcie_ops_v2,
> .startup = mtk_pcie_startup_port_v2,
> .setup_irq = mtk_pcie_setup_irq,
> @@ -1210,6 +1275,7 @@ static const struct mtk_pcie_soc mtk_pcie_soc_mt2712 = {
>
> static const struct mtk_pcie_soc mtk_pcie_soc_mt7622 = {
> .need_fix_class_id = true,
> + .pm_support = true,
> .ops = &mtk_pcie_ops_v2,
> .startup = mtk_pcie_startup_port_v2,
> .setup_irq = mtk_pcie_setup_irq,
> @@ -1229,6 +1295,7 @@ static struct platform_driver mtk_pcie_driver = {
> .name = "mtk-pcie",
> .of_match_table = mtk_pcie_ids,
> .suppress_bind_attrs = true,
> + .pm = &mtk_pcie_pm_ops,
> },
> };
> builtin_platform_driver(mtk_pcie_driver);
> --
> 2.6.4
>
Kind regards
Uffe
