Hi Pali,
Thanks for your comments.
On Mon, May 31, 2021 at 3:14 PM Pali Rohár <pali@xxxxxxxxxx> wrote:
>
> On Saturday 15 May 2021 14:40:53 Sergio Paracuellos wrote:
> > This patch adds a driver for the PCIe controller of MT7621 SoC.
> >
> > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@xxxxxxxxx>
> > ---
> > arch/mips/pci/Makefile | 1 +
> > arch/mips/pci/pci-mt7621.c | 624 +++++++++++++++++++++++++++++++++++++
> > arch/mips/ralink/Kconfig | 9 +-
> > 3 files changed, 633 insertions(+), 1 deletion(-)
> > create mode 100644 arch/mips/pci/pci-mt7621.c
> >
> > diff --git a/arch/mips/pci/Makefile b/arch/mips/pci/Makefile
> > index f3eecc065e5c..178c550739c4 100644
> > --- a/arch/mips/pci/Makefile
> > +++ b/arch/mips/pci/Makefile
> > @@ -24,6 +24,7 @@ obj-$(CONFIG_PCI_AR2315) += pci-ar2315.o
> > obj-$(CONFIG_SOC_AR71XX) += pci-ar71xx.o
> > obj-$(CONFIG_PCI_AR724X) += pci-ar724x.o
> > obj-$(CONFIG_PCI_XTALK_BRIDGE) += pci-xtalk-bridge.o
> > +obj-$(CONFIG_PCI_MT7621) += pci-mt7621.o
> > #
> > # These are still pretty much in the old state, watch, go blind.
> > #
> > diff --git a/arch/mips/pci/pci-mt7621.c b/arch/mips/pci/pci-mt7621.c
> > new file mode 100644
> > index 000000000000..fe1945819d25
> > --- /dev/null
> > +++ b/arch/mips/pci/pci-mt7621.c
> ...
> > +static int mt7621_pcie_enable_ports(struct mt7621_pcie *pcie)
> > +{
> > + struct device *dev = pcie->dev;
> > + struct mt7621_pcie_port *port;
> > + u8 num_slots_enabled = 0;
> > + u32 slot;
> > + u32 val;
> > + int err;
> > +
> > + /* Setup MEMWIN and IOWIN */
> > + pcie_write(pcie, 0xffffffff, RALINK_PCI_MEMBASE);
> > + pcie_write(pcie, pcie->io.start, RALINK_PCI_IOBASE);
> > +
> > + list_for_each_entry(port, &pcie->ports, list) {
> > + if (port->enabled) {
> > + err = clk_prepare_enable(port->clk);
> > + if (err) {
> > + dev_err(dev, "enabling clk pcie%d\n", slot);
> > + return err;
> > + }
> > +
> > + mt7621_pcie_enable_port(port);
> > + dev_info(dev, "PCIE%d enabled\n", port->slot);
> > + num_slots_enabled++;
> > + }
> > + }
> > +
> > + for (slot = 0; slot < num_slots_enabled; slot++) {
> > + val = read_config(pcie, slot, PCI_COMMAND);
> > + val |= PCI_COMMAND_MASTER;
> > + write_config(pcie, slot, PCI_COMMAND, val);
>
> Hello! Is this part of code correct? Because it looks strange if PCIe
> controller driver automatically enables PCI bus mastering, prior device
> driver initialize itself.
>
> Moreover kernel has already function pci_set_master() for this purpose
> which is used by device drivers.
>
> So I think this code can confuse some device drivers...
I agree that we have pci_set_master() to be used in pci device driver
code. Original controller driver set this bit for enabled slots. Since
there is no documentation at all for the PCI in this SoC I have
maintained the setting in the driver in a cleaner way. See original
driver code and the setting here [0]. There is no other reason than
that. I am ok with removing this from here and testing with my two
devices that everything is still ok if having this setting in the pci
controller driver is a real problem.
[0]: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/tree/drivers/staging/mt7621-pci/pci-mt7621.c?h=v4.18#n676
Best regards,
Sergio Paracuellos
>
> > + /* configure RC FTS number to 250 when it leaves L0s */
> > + val = read_config(pcie, slot, PCIE_FTS_NUM);
> > + val &= ~PCIE_FTS_NUM_MASK;
> > + val |= PCIE_FTS_NUM_L0(0x50);
> > + write_config(pcie, slot, PCIE_FTS_NUM, val);
> > + }
> > +
> > + return 0;
> > +}
