From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 20 Jun 2019 16:22:31 +0100 From: Lorenzo Pieralisi Subject: Re: [PATCH V6 06/27] PCI: tegra: Add PCIe Gen2 link speed support Message-ID: <20190620152231.GB23729@e121166-lin.cambridge.arm.com> References: <20190618180206.4908-1-mmaddireddy@nvidia.com> <20190618180206.4908-7-mmaddireddy@nvidia.com> <20190620143251.GB31996@e121166-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: To: Manikanta Maddireddy Cc: thierry.reding@gmail.com, bhelgaas@google.com, robh+dt@kernel.org, mark.rutland@arm.com, jonathanh@nvidia.com, vidyas@nvidia.com, linux-tegra@vger.kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org List-ID: On Thu, Jun 20, 2019 at 08:27:15PM +0530, Manikanta Maddireddy wrote: > > > On 20-Jun-19 8:02 PM, Lorenzo Pieralisi wrote: > > On Tue, Jun 18, 2019 at 11:31:45PM +0530, Manikanta Maddireddy wrote: > >> Tegra124, Tegra132, Tegra210 and Tegra186 support Gen2 link speed. After > >> PCIe link is up in Gen1, set target link speed as Gen2 and retrain link. > >> Link switches to Gen2 speed if Gen2 capable end point is connected, else > >> link stays in Gen1. > >> > >> Per PCIe 4.0r0.9 sec 7.6.3.7 implementation note, driver need to wait for > >> PCIe LTSSM to come back from recovery before retraining the link. > >> > >> Signed-off-by: Manikanta Maddireddy > >> Acked-by: Thierry Reding > >> --- > >> V6: No change > >> > >> V5: No change > >> > >> V4: No change > >> > >> V3: Added blank line after each while loop. > >> > >> V2: Changed "for loop" to "while", to make it compact and handled coding > >> style comments. > >> > >> drivers/pci/controller/pci-tegra.c | 64 ++++++++++++++++++++++++++++++ > >> 1 file changed, 64 insertions(+) > >> > >> diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c > >> index 5e9fcef5f8eb..5d19067f7193 100644 > >> --- a/drivers/pci/controller/pci-tegra.c > >> +++ b/drivers/pci/controller/pci-tegra.c > >> @@ -191,6 +191,8 @@ > >> #define RP_LINK_CONTROL_STATUS_DL_LINK_ACTIVE 0x20000000 > >> #define RP_LINK_CONTROL_STATUS_LINKSTAT_MASK 0x3fff0000 > >> > >> +#define RP_LINK_CONTROL_STATUS_2 0x000000b0 > >> + > >> #define PADS_CTL_SEL 0x0000009c > >> > >> #define PADS_CTL 0x000000a0 > >> @@ -226,6 +228,7 @@ > >> #define PADS_REFCLK_CFG_DRVI_SHIFT 12 /* 15:12 */ > >> > >> #define PME_ACK_TIMEOUT 10000 > >> +#define LINK_RETRAIN_TIMEOUT 100000 /* in usec */ > >> > >> struct tegra_msi { > >> struct msi_controller chip; > >> @@ -2089,6 +2092,64 @@ static bool tegra_pcie_port_check_link(struct tegra_pcie_port *port) > >> return false; > >> } > >> > >> +static void tegra_pcie_change_link_speed(struct tegra_pcie *pcie) > >> +{ > >> + struct device *dev = pcie->dev; > >> + struct tegra_pcie_port *port, *tmp; > >> + ktime_t deadline; > >> + u32 value; > >> + > >> + list_for_each_entry_safe(port, tmp, &pcie->ports, list) { > > And the reason to use the _safe version is ? > > > > Lorenzo > > This function is called in probe and resume_noirq. list entry is deleted in > remove, I don't see any scenario where it can cause a race condition. > It is fine to drop _safe. I will fix it in next version. I will do it myself, it is not a fundamental issue, do not send another version. Thanks, Lorenzo