Re: [Patch v4 10/10] PCI: tegra194: add interconnect support in Tegra234

[Sumit Gupta <sumitg@xxxxxxxxxx>]

On 28/03/23 23:23, Bjorn Helgaas wrote:
> External email: Use caution opening links or attachments
>
>
> Capitalize subject line please, to match pcie-tegra194.c history.
>
> On Mon, Mar 27, 2023 at 09:44:26PM +0530, Sumit Gupta wrote:
> > Add support to request DRAM bandwidth with Memory Interconnect
> > in Tegra234 SoC. The DRAM BW required for different modes depends
> > on speed (Gen-1/2/3/4) and width/lanes (x1/x2/x4/x8).
> >
> > Suggested-by: Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>
> > Signed-off-by: Sumit Gupta <sumitg@xxxxxxxxxx>
> > ---
> >   drivers/pci/controller/dwc/pcie-tegra194.c | 40 +++++++++++++++++-----
> >   1 file changed, 32 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> > index 09825b4a075e..d2513c9d3feb 100644
> > --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> > +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> > @@ -15,6 +15,7 @@
> >   #include <linux/gpio.h>
> >   #include <linux/gpio/consumer.h>
> >   #include <linux/interrupt.h>
> > +#include <linux/interconnect.h>
>
> Almost alphabetized, swap interrupt.h and interconnect.h.
Ok, will swap.

> >   #include <linux/iopoll.h>
> >   #include <linux/kernel.h>
> >   #include <linux/module.h>
> > @@ -287,6 +288,7 @@ struct tegra_pcie_dw {
> >        unsigned int pex_rst_irq;
> >        int ep_state;
> >        long link_status;
> > +     struct icc_path *icc_path;
> >   };
> >
> >   static inline struct tegra_pcie_dw *to_tegra_pcie(struct dw_pcie *pci)
> > @@ -309,6 +311,24 @@ struct tegra_pcie_soc {
> >        enum dw_pcie_device_mode mode;
> >   };
> >
> > +static void tegra_pcie_icc_set(struct tegra_pcie_dw *pcie)
> > +{
> > +     struct dw_pcie *pci = &pcie->pci;
> > +     u32 val, speed, width;
> > +
> > +     val = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA);
> > +
> > +     speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, val);
> > +     width = FIELD_GET(PCI_EXP_LNKSTA_NLW, val);
> > +
> > +     val = width * (PCIE_SPEED2MBS_ENC(pcie_link_speed[speed]) / BITS_PER_BYTE);
> > +
> > +     if (icc_set_bw(pcie->icc_path, MBps_to_icc(val), 0))
> > +             dev_err(pcie->dev, "can't set bw[%u]\n", val);
> > +
> > +     clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
>
> Array bounds violation; PCI_EXP_LNKSTA_CLS is 0x000f, so possible
> speed (CLS) values are 0..0xf and "speed - 1" values are -1..0xe.
>
> pcie_gen_freq[] is of size 4 (valid indices 0..3).
>
> I see that you're just *moving* this code, but might as well fix it.
Thank you for the review.
Will include the below change in the same patch. Please let me know if 
any issue.

 -       clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
 +       if (speed && (speed <= ARRAY_SIZE(pcie_gen_freq)))
 +               clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
 +       else
 +               clk_set_rate(pcie->core_clk, pcie_gen_freq[0]);

Thank you,
Sumit Gupta

> > +}
> > +
> >   static void apply_bad_link_workaround(struct dw_pcie_rp *pp)
> >   {
> >        struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > @@ -452,14 +472,12 @@ static irqreturn_t tegra_pcie_ep_irq_thread(int irq, void *arg)
> >        struct tegra_pcie_dw *pcie = arg;
> >        struct dw_pcie_ep *ep = &pcie->pci.ep;
> >        struct dw_pcie *pci = &pcie->pci;
> > -     u32 val, speed;
> > +     u32 val;
> >
> >        if (test_and_clear_bit(0, &pcie->link_status))
> >                dw_pcie_ep_linkup(ep);
> >
> > -     speed = dw_pcie_readw_dbi(pci, pcie->pcie_cap_base + PCI_EXP_LNKSTA) &
> > -             PCI_EXP_LNKSTA_CLS;
> > -     clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
> > +     tegra_pcie_icc_set(pcie);