Re: [PATCH 09/12] PCI: tegra: Enable PCIe xclk clock clamping

[Manikanta Maddireddy <mmaddireddy-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

On 29-Oct-17 3:13 PM, Vidya Sagar wrote:
> 
> 
> On Saturday 28 October 2017 12:59 AM, Manikanta Maddireddy wrote:
>> This patch enables PCIe xlck clock clamping by pad control. Pad control
>> asserts UPHY lane sleep signal when L1 entry signal received from PCIe.
>> UPHY sleep signal assertion is done per lane. Default clamp threshold
>> margin is not enough to assert all UPHY lane sleep signals. Increase
>> the clamp threshold in Tegra124, 132, 210 and 186.
>>
>> Signed-off-by: Manikanta Maddireddy <mmaddireddy-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>> ---
>>   drivers/pci/host/pci-tegra.c | 28 ++++++++++++++++++++++++++--
>>   1 file changed, 26 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
>> index 6028d5f3d5bb..8fbc5950785a 100644
>> --- a/drivers/pci/host/pci-tegra.c
>> +++ b/drivers/pci/host/pci-tegra.c
>> @@ -224,8 +224,14 @@
>>   #define  RP_VEND_CTL2_PCA_ENABLE (1 << 7)
>>     #define RP_PRIV_MISC    0x00000fe0
>> -#define  RP_PRIV_MISC_PRSNT_MAP_EP_PRSNT (0xe << 0)
>> -#define  RP_PRIV_MISC_PRSNT_MAP_EP_ABSNT (0xf << 0)
>> +#define  RP_PRIV_MISC_PRSNT_MAP_EP_PRSNT        (0xe << 0)
>> +#define  RP_PRIV_MISC_PRSNT_MAP_EP_ABSNT        (0xf << 0)
>> +#define  RP_PRIV_MISC_CTLR_CLK_CLAMP_THRESHOLD_MASK    (0x7f << 16)
>> +#define  RP_PRIV_MISC_CTLR_CLK_CLAMP_THRESHOLD        (0xf << 16)
>> +#define  RP_PRIV_MISC_CTLR_CLK_CLAMP_ENABLE        (1 << 23)
>> +#define  RP_PRIV_MISC_TMS_CLK_CLAMP_THRESHOLD_MASK    (0x7f << 24)
>> +#define  RP_PRIV_MISC_TMS_CLK_CLAMP_THRESHOLD        (0xf << 24)
>> +#define  RP_PRIV_MISC_TMS_CLK_CLAMP_ENABLE        (1 << 31)
>>   
> BIT macro is preferred here.
Left shift is used everywhere, so to be inline with that I used same format
>>   #define RP_LINK_CONTROL_STATUS            0x00000090
>>   #define  RP_LINK_CONTROL_STATUS_DL_LINK_ACTIVE    0x20000000
>> @@ -300,6 +306,7 @@ struct tegra_pcie_soc {
>>       bool force_pca_enable;
>>       bool program_uphy;
>>       bool program_ectl_settings;
>> +    bool update_clamp_threshold;
>>   };
>>     static inline struct tegra_msi *to_tegra_msi(struct msi_controller *chip)
>> @@ -2156,6 +2163,7 @@ static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port)
>>     static void tegra_pcie_apply_sw_fixup(struct tegra_pcie_port *port)
>>   {
>> +    const struct tegra_pcie_soc *soc = port->pcie->soc;
>>       unsigned long value;
>>         /* Optimal settings to enhance bandwidth */
>> @@ -2170,6 +2178,17 @@ static void tegra_pcie_apply_sw_fixup(struct tegra_pcie_port *port)
>>       value = readl(port->base + RP_VEND_XP_BIST);
>>       value |= RP_VEND_XP_BIST_GOTO_L1_L2_AFTER_DLLP_DONE;
>>       writel(value, port->base + RP_VEND_XP_BIST);
>> +
>> +    value = readl(port->base + RP_PRIV_MISC);
>> +    value |= (RP_PRIV_MISC_CTLR_CLK_CLAMP_ENABLE |
>> +             RP_PRIV_MISC_TMS_CLK_CLAMP_ENABLE);
>> +    if (soc->update_clamp_threshold) {
>> +        value &= ~(RP_PRIV_MISC_CTLR_CLK_CLAMP_THRESHOLD_MASK |
>> +                RP_PRIV_MISC_TMS_CLK_CLAMP_THRESHOLD_MASK);
>> +        value |= (RP_PRIV_MISC_CTLR_CLK_CLAMP_THRESHOLD |
>> +                RP_PRIV_MISC_TMS_CLK_CLAMP_THRESHOLD);
>> +    }
>> +    writel(value, port->base + RP_PRIV_MISC);
>>   }
>>   /*
>>    * FIXME: If there are no PCIe cards attached, then calling this function
>> @@ -2306,6 +2325,7 @@ static const struct tegra_pcie_soc tegra20_pcie = {
>>       .force_pca_enable = false,
>>       .program_uphy = true,
>>       .program_ectl_settings = false,
>> +    .update_clamp_threshold = false,
>>   };
>>     static const struct tegra_pcie_soc tegra30_pcie = {
>> @@ -2323,6 +2343,7 @@ static const struct tegra_pcie_soc tegra30_pcie = {
>>       .force_pca_enable = false,
>>       .program_uphy = true,
>>       .program_ectl_settings = false,
>> +    .update_clamp_threshold = false,
>>   };
>>     static const struct tegra_pcie_soc tegra124_pcie = {
>> @@ -2339,6 +2360,7 @@ static const struct tegra_pcie_soc tegra124_pcie = {
>>       .force_pca_enable = false,
>>       .program_uphy = true,
>>       .program_ectl_settings = false,
>> +    .update_clamp_threshold = true,
>>   };
>>     static const struct tegra_pcie_soc tegra210_pcie = {
>> @@ -2363,6 +2385,7 @@ static const struct tegra_pcie_soc tegra210_pcie = {
>>       .force_pca_enable = true,
>>       .program_uphy = true,
>>       .program_ectl_settings = true,
>> +    .update_clamp_threshold = true,
>>   };
>>     static const struct tegra_pcie_soc tegra186_pcie = {
>> @@ -2380,6 +2403,7 @@ static const struct tegra_pcie_soc tegra186_pcie = {
>>       .force_pca_enable = false,
>>       .program_uphy = false,
>>       .program_ectl_settings = false,
>> +    .update_clamp_threshold = false,
>>   };
>>     static const struct of_device_id tegra_pcie_of_match[] = {
>