From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Niklas Cassel <cassel@kernel.org>
Cc: "Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Rob Herring" <robh@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Jonathan Hunter" <jonathanh@nvidia.com>,
"Jingoo Han" <jingoohan1@gmail.com>,
"Gustavo Pimentel" <gustavo.pimentel@synopsys.com>,
linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-kernel@vger.kernel.org, mhi@lists.linux.dev,
linux-tegra@vger.kernel.org
Subject: Re: [PATCH 10/11] PCI: qcom-ep: Rework {start/stop}_link() callbacks implementation
Date: Tue, 26 Mar 2024 14:03:38 +0530 [thread overview]
Message-ID: <20240326083338.GI9565@thinkpad> (raw)
In-Reply-To: <Zf2tjht4TR7Irewd@ryzen>
On Fri, Mar 22, 2024 at 05:10:54PM +0100, Niklas Cassel wrote:
> On Thu, Mar 14, 2024 at 08:53:49PM +0530, Manivannan Sadhasivam wrote:
> > DWC specific start_link() and stop_link() callbacks are supposed to start
> > and stop the link training of the PCIe bus. But the current implementation
> > of this driver enables/disables the PERST# IRQ.
> >
> > Even though this is not causing any issues, this creates inconsistency
> > among the controller drivers. So for the sake of consistency, let's just
> > start/stop the link training in these callbacks.
> >
> > Also, PERST# IRQ is now enabled from the start itself, thus allowing the
> > controller driver to initialize the registers when PERST# gets deasserted
> > without waiting for the user intervention though configfs.
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
>
> Nice change:
> Reviewed-by: Niklas Cassel <cassel@kernel.org>
>
> If you dump LTSSM after a PERST assert + deassert,
> using e.g. dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1);
> to dump the debug registers (see dw_pcie_link_up())
> do you see that PCIE_PORT_DEBUG1_LINK_IN_TRAINING is set?
>
> I was thinking that perhaps there was a thought behind
> this original design, that you had to explicitly set
> LTSSM_EN after a fundamental core reset, because it
> would get cleared?
>
Well, you are right. I was hoping to get an answer from Kishon/Vidya, but you
throwed the light. I will drop these 2 patches.
Thanks!
- Mani
> (It it is implemented like signals and not registers,
> then this change should be fine.)
>
>
> Kind regards,
> Niklas
>
>
> > drivers/pci/controller/dwc/pcie-qcom-ep.c | 21 +++++++++++++--------
> > 1 file changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > index 811f250e967a..653e4ace0a07 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > @@ -122,6 +122,9 @@
> > /* PARF_CFG_BITS register fields */
> > #define PARF_CFG_BITS_REQ_EXIT_L1SS_MSI_LTR_EN BIT(1)
> >
> > +/* PARF_LTSSM register fields */
> > +#define LTSSM_EN BIT(8)
> > +
> > /* ELBI registers */
> > #define ELBI_SYS_STTS 0x08
> > #define ELBI_CS2_ENABLE 0xa4
> > @@ -250,8 +253,12 @@ static int qcom_pcie_dw_link_up(struct dw_pcie *pci)
> > static int qcom_pcie_dw_start_link(struct dw_pcie *pci)
> > {
> > struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
> > + u32 val;
> >
> > - enable_irq(pcie_ep->perst_irq);
> > + /* Enable LTSSM */
> > + val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
> > + val |= LTSSM_EN;
> > + writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);
> >
> > return 0;
> > }
> > @@ -259,8 +266,12 @@ static int qcom_pcie_dw_start_link(struct dw_pcie *pci)
> > static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
> > {
> > struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
> > + u32 val;
> >
> > - disable_irq(pcie_ep->perst_irq);
> > + /* Disable LTSSM */
> > + val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
> > + val &= ~LTSSM_EN;
> > + writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);
> > }
> >
> > static void qcom_pcie_dw_write_dbi2(struct dw_pcie *pci, void __iomem *base,
> > @@ -484,11 +495,6 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
> >
> > dw_pcie_ep_init_notify(&pcie_ep->pci.ep);
> >
> > - /* Enable LTSSM */
> > - val = readl_relaxed(pcie_ep->parf + PARF_LTSSM);
> > - val |= BIT(8);
> > - writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);
> > -
> > return 0;
> >
> > err_disable_resources:
> > @@ -707,7 +713,6 @@ static int qcom_pcie_ep_enable_irq_resources(struct platform_device *pdev,
> > }
> >
> > pcie_ep->perst_irq = gpiod_to_irq(pcie_ep->reset);
> > - irq_set_status_flags(pcie_ep->perst_irq, IRQ_NOAUTOEN);
> > ret = devm_request_threaded_irq(&pdev->dev, pcie_ep->perst_irq, NULL,
> > qcom_pcie_ep_perst_irq_thread,
> > IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> >
> > --
> > 2.25.1
> >
>
--
மணிவண்ணன் சதாசிவம்
next prev parent reply other threads:[~2024-03-26 8:33 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-14 15:23 [PATCH 00/11] PCI: endpoint: Make host reboot handling more robust Manivannan Sadhasivam
2024-03-14 15:23 ` [PATCH 01/11] PCI: qcom-ep: Disable resources unconditionally during PERST# assert Manivannan Sadhasivam
2024-03-22 16:08 ` Niklas Cassel
2024-03-26 7:44 ` Manivannan Sadhasivam
2024-03-26 10:24 ` Niklas Cassel
2024-03-26 11:10 ` Manivannan Sadhasivam
2024-03-26 13:47 ` Niklas Cassel
2024-03-26 13:55 ` Manivannan Sadhasivam
2024-03-26 10:37 ` Niklas Cassel
2024-03-14 15:23 ` [PATCH 02/11] PCI: endpoint: Decouple EPC and PCIe bus specific events Manivannan Sadhasivam
2024-03-22 16:08 ` Niklas Cassel
2024-03-26 7:49 ` Manivannan Sadhasivam
2024-03-14 15:23 ` [PATCH 03/11] PCI: endpoint: Rename core_init() callback in 'struct pci_epc_event_ops' to init() Manivannan Sadhasivam
2024-03-22 16:08 ` Niklas Cassel
2024-03-26 7:56 ` Manivannan Sadhasivam
2024-03-14 15:23 ` [PATCH 04/11] PCI: epf-test: Refactor pci_epf_test_unbind() function Manivannan Sadhasivam
2024-03-22 16:09 ` Niklas Cassel
2024-03-26 7:58 ` Manivannan Sadhasivam
2024-03-14 15:23 ` [PATCH 05/11] PCI: epf-{mhi/test}: Move DMA initialization to EPC init callback Manivannan Sadhasivam
2024-03-22 16:10 ` Niklas Cassel
2024-03-26 8:26 ` Manivannan Sadhasivam
2024-03-26 11:05 ` Niklas Cassel
2024-03-26 14:27 ` Niklas Cassel
2024-03-27 6:20 ` Manivannan Sadhasivam
2024-03-27 6:18 ` Manivannan Sadhasivam
2024-03-27 11:39 ` Niklas Cassel
2024-03-28 18:42 ` Vinod Koul
2024-04-04 8:44 ` Niklas Cassel
2024-04-22 7:55 ` Manivannan Sadhasivam
2024-04-22 9:30 ` Niklas Cassel
2024-03-14 15:23 ` [PATCH 06/11] PCI: endpoint: Introduce EPC 'deinit' event and notify the EPF drivers Manivannan Sadhasivam
2024-03-22 16:10 ` Niklas Cassel
2024-03-26 8:31 ` Manivannan Sadhasivam
2024-03-14 15:23 ` [PATCH 07/11] PCI: dwc: ep: Add a generic dw_pcie_ep_linkdown() API to handle Link Down event Manivannan Sadhasivam
2024-03-22 16:10 ` Niklas Cassel
2024-03-27 18:06 ` Niklas Cassel
2024-04-01 16:34 ` Manivannan Sadhasivam
2024-03-14 15:23 ` [PATCH 08/11] PCI: qcom-ep: Use the " Manivannan Sadhasivam
2024-03-14 15:23 ` [PATCH 09/11] PCI: epf-test: Handle " Manivannan Sadhasivam
2024-03-22 16:10 ` Niklas Cassel
2024-03-14 15:23 ` [PATCH 10/11] PCI: qcom-ep: Rework {start/stop}_link() callbacks implementation Manivannan Sadhasivam
2024-03-22 16:10 ` Niklas Cassel
2024-03-26 8:33 ` Manivannan Sadhasivam [this message]
2024-03-14 15:23 ` [PATCH 11/11] PCI: tegra194: " Manivannan Sadhasivam
2024-03-22 16:11 ` Niklas Cassel
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