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SubjectRe: [Patch v4 10/10] PCI: tegra194: add interconnect support in Tegra234
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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@nvidia.com>
>> Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
>> ---
>> 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);

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