From: Damien Le Moal <dlemoal@kernel.org>
To: Shawn Lin <shawn.lin@rock-chips.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Heiko Stuebner <heiko@sntech.de>,
linux-pci@vger.kernel.org
Cc: "Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
linux-rockchip@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 1/2] PCI: rockchip-host: Fix rockchip_pcie_host_init_port() PERST# handling
Date: Sat, 13 Apr 2024 09:41:19 +0900 [thread overview]
Message-ID: <20240413004120.1099089-2-dlemoal@kernel.org> (raw)
In-Reply-To: <20240413004120.1099089-1-dlemoal@kernel.org>
The PCIe specifications (PCIe CEM r5.1, sec 2.9.2) mandate that the
PERST# signal must remain asserted for at least 100 usec (Tperst-clk)
after the PCIe reference clock becomes stable (if a reference clock is
supplied), and for at least 100 msec after the power is stable (Tpvperl,
defined by the macro PCIE_T_PVPERL_MS).
Modify rockchip_pcie_host_init_port() to satisfy these constraints by
adding a sleep period before deasserting PERST# using the ep_gpio GPIO.
Since Tperst-clk is the shorter wait time, add an msleep() call for the
longer PCIE_T_PVPERL_MS milliseconds to handle both timing requirements.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
drivers/pci/controller/pcie-rockchip-host.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
index 300b9dc85ecc..fc868251e570 100644
--- a/drivers/pci/controller/pcie-rockchip-host.c
+++ b/drivers/pci/controller/pcie-rockchip-host.c
@@ -322,6 +322,7 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
rockchip_pcie_write(rockchip, PCIE_CLIENT_LINK_TRAIN_ENABLE,
PCIE_CLIENT_CONFIG);
+ msleep(PCIE_T_PVPERL_MS);
gpiod_set_value_cansleep(rockchip->ep_gpio, 1);
/* 500ms timeout value should be enough for Gen1/2 training */
--
2.44.0
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next prev parent reply other threads:[~2024-04-13 0:41 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-13 0:41 [PATCH v4 0/2] rockchip rk3399 port initialization fixes Damien Le Moal
2024-04-13 0:41 ` Damien Le Moal [this message]
2024-04-15 6:48 ` [PATCH v4 1/2] PCI: rockchip-host: Fix rockchip_pcie_host_init_port() PERST# handling Manivannan Sadhasivam
2024-04-13 0:41 ` [PATCH v4 2/2] PCI: rockchip-host: Wait 100ms after reset before starting configuration Damien Le Moal
2024-04-15 6:50 ` Manivannan Sadhasivam
2024-05-15 21:14 ` [PATCH v4 0/2] rockchip rk3399 port initialization fixes Bjorn Helgaas
2024-05-17 11:19 ` Krzysztof Wilczyński
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