| Message ID | 20240329084407.1050307-1-dlemoal@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PCI: rockchip-host: Fix rockchip_pcie_host_init_port() PERST handling | expand |
Observing the timing is the important thing here, if you can wedge that into the subject somehow. On Fri, Mar 29, 2024 at 05:44:07PM +0900, Damien Le Moal wrote: > The PCI specifications mandate that PERST be asserted for at least > 100ms. Make sure that is done in rockchip_pcie_host_init_port() by > adding a 100ms sleep before bringing back PESRT signal to high using the > ep_gpio GPIO. Comments are also added to clarify this behavior. "PERST#" in spec, and to make the "assert" and "set value to 0" all match up. s/PESRT/PERST#/ > Signed-off-by: Damien Le Moal <dlemoal@kernel.org> > --- > drivers/pci/controller/pcie-rockchip-host.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c > index 300b9dc85ecc..d526b9d26c18 100644 > --- a/drivers/pci/controller/pcie-rockchip-host.c > +++ b/drivers/pci/controller/pcie-rockchip-host.c > @@ -294,6 +294,7 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip) > int err, i = MAX_LANE_NUM; > u32 status; > > + /* Assert PERST */ > gpiod_set_value_cansleep(rockchip->ep_gpio, 0); > > err = rockchip_pcie_init_port(rockchip); > @@ -322,6 +323,11 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip) > rockchip_pcie_write(rockchip, PCIE_CLIENT_LINK_TRAIN_ENABLE, > PCIE_CLIENT_CONFIG); > > + /* > + * PCIe specifications mandate that PERST be asserted for at > + * least 100ms. > + */ > + msleep(100); Specific rev, section citation? And a name for the parameter if there is one (T_PVPERL, etc). And hopefully a macro along the lines of PCIE_T_PVPERL_MS since this isn't rockchip-specific. > gpiod_set_value_cansleep(rockchip->ep_gpio, 1); > > /* 500ms timeout value should be enough for Gen1/2 training */ > -- > 2.44.0 >
diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c index 300b9dc85ecc..d526b9d26c18 100644 --- a/drivers/pci/controller/pcie-rockchip-host.c +++ b/drivers/pci/controller/pcie-rockchip-host.c @@ -294,6 +294,7 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip) int err, i = MAX_LANE_NUM; u32 status; + /* Assert PERST */ gpiod_set_value_cansleep(rockchip->ep_gpio, 0); err = rockchip_pcie_init_port(rockchip); @@ -322,6 +323,11 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip) rockchip_pcie_write(rockchip, PCIE_CLIENT_LINK_TRAIN_ENABLE, PCIE_CLIENT_CONFIG); + /* + * PCIe specifications mandate that PERST be asserted for at + * least 100ms. + */ + msleep(100); gpiod_set_value_cansleep(rockchip->ep_gpio, 1); /* 500ms timeout value should be enough for Gen1/2 training */
The PCI specifications mandate that PERST be asserted for at least 100ms. Make sure that is done in rockchip_pcie_host_init_port() by adding a 100ms sleep before bringing back PESRT signal to high using the ep_gpio GPIO. Comments are also added to clarify this behavior. Signed-off-by: Damien Le Moal <dlemoal@kernel.org> --- drivers/pci/controller/pcie-rockchip-host.c | 6 ++++++ 1 file changed, 6 insertions(+)