The parameter detect_quiet_min_delay can be used to program the minimum
time that LTSSM waits on entering Detect.Quiet state.
00 : 0us minimum wait time in Detect.Quiet state.
01 : 100us minimum wait time in Detect.Quiet state.
10 : 1000us minimum wait time in Detect.Quiet state.
11 : 2000us minimum wait time in Detect.Quiet state.
As per PCIe specification, all Receivers must meet the Z-RX-DC
specification for 2.5 GT/s within 1000us of entering Detect.Quiet LTSSM
substate. The LTSSM must stay in this substate until the ZRXDC
specification for 2.5 GT/s is met.
Signed-off-by: Nadeem Athani <[email protected]>
---
drivers/pci/controller/cadence/pcie-cadence-host.c | 22 ++++++++++++++++++++++
drivers/pci/controller/cadence/pcie-cadence.h | 10 ++++++++++
2 files changed, 32 insertions(+)
diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index 73dcf8cf98fb..056161b3fe65 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -461,6 +461,20 @@ static int cdns_pcie_host_init(struct device *dev,
return cdns_pcie_host_init_address_translation(rc);
}
+static void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie_rc *rc)
+{
+ struct cdns_pcie *pcie = &rc->pcie;
+ u32 delay = rc->detect_quiet_min_delay;
+ u32 ltssm_control_cap;
+
+ ltssm_control_cap = cdns_pcie_readl(pcie, CDNS_PCIE_LTSSM_CONTROL_CAP);
+ ltssm_control_cap = ((ltssm_control_cap &
+ ~CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK) |
+ CDNS_PCIE_DETECT_QUIET_MIN_DELAY(delay));
+
+ cdns_pcie_writel(pcie, CDNS_PCIE_LTSSM_CONTROL_CAP, ltssm_control_cap);
+}
+
int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
{
struct device *dev = rc->pcie.dev;
@@ -485,6 +499,10 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
rc->device_id = 0xffff;
of_property_read_u32(np, "device-id", &rc->device_id);
+ rc->detect_quiet_min_delay = 0;
+ of_property_read_u32(np, "detect-quiet-min-delay",
+ &rc->detect_quiet_min_delay);
+
pcie->reg_base = devm_platform_ioremap_resource_byname(pdev, "reg");
if (IS_ERR(pcie->reg_base)) {
dev_err(dev, "missing \"reg\"\n");
@@ -497,6 +515,10 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
return PTR_ERR(rc->cfg_base);
rc->cfg_res = res;
+ /* Default Detect.Quiet state delay is 0 */
+ if (rc->detect_quiet_min_delay)
+ cdns_pcie_detect_quiet_min_delay_set(rc);
+
ret = cdns_pcie_start_link(pcie);
if (ret) {
dev_err(dev, "Failed to start link\n");
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index 254d2570f8c9..f2d3cca2c707 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -189,6 +189,14 @@
/* AXI link down register */
#define CDNS_PCIE_AT_LINKDOWN (CDNS_PCIE_AT_BASE + 0x0824)
+/* LTSSM Capabilities register */
+#define CDNS_PCIE_LTSSM_CONTROL_CAP (CDNS_PCIE_LM_BASE + 0x0054)
+#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK GENMASK(2, 1)
+#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY_SHIFT 1
+#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY(delay) \
+ (((delay) << CDNS_PCIE_DETECT_QUIET_MIN_DELAY_SHIFT) & \
+ CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK)
+
enum cdns_pcie_rp_bar {
RP_BAR_UNDEFINED = -1,
RP_BAR0,
@@ -289,6 +297,7 @@ struct cdns_pcie {
* single function at a time
* @vendor_id: PCI vendor ID
* @device_id: PCI device ID
+ * @detect_quiet_min_delay: LTSSM Detect Quite state min. delay
* @avail_ib_bar: Satus of RP_BAR0, RP_BAR1 and RP_NO_BAR if it's free or
* available
* @quirk_retrain_flag: Retrain link as quirk for PCIe Gen2
@@ -299,6 +308,7 @@ struct cdns_pcie_rc {
void __iomem *cfg_base;
u32 vendor_id;
u32 device_id;
+ u32 detect_quiet_min_delay;
bool avail_ib_bar[CDNS_PCIE_RP_MAX_IB];
bool quirk_retrain_flag;
};
--
2.15.0
Hi Nadeem,
On 09/03/21 1:01 pm, Nadeem Athani wrote:
> The parameter detect_quiet_min_delay can be used to program the minimum
> time that LTSSM waits on entering Detect.Quiet state.
> 00 : 0us minimum wait time in Detect.Quiet state.
> 01 : 100us minimum wait time in Detect.Quiet state.
> 10 : 1000us minimum wait time in Detect.Quiet state.
> 11 : 2000us minimum wait time in Detect.Quiet state.
>
> As per PCIe specification, all Receivers must meet the Z-RX-DC
> specification for 2.5 GT/s within 1000us of entering Detect.Quiet LTSSM
> substate. The LTSSM must stay in this substate until the ZRXDC
> specification for 2.5 GT/s is met.
>
> Signed-off-by: Nadeem Athani <[email protected]>
> ---
> drivers/pci/controller/cadence/pcie-cadence-host.c | 22 ++++++++++++++++++++++
> drivers/pci/controller/cadence/pcie-cadence.h | 10 ++++++++++
> 2 files changed, 32 insertions(+)
>
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index 73dcf8cf98fb..056161b3fe65 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -461,6 +461,20 @@ static int cdns_pcie_host_init(struct device *dev,
> return cdns_pcie_host_init_address_translation(rc);
> }
>
> +static void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie_rc *rc)
> +{
> + struct cdns_pcie *pcie = &rc->pcie;
> + u32 delay = rc->detect_quiet_min_delay;
> + u32 ltssm_control_cap;
> +
> + ltssm_control_cap = cdns_pcie_readl(pcie, CDNS_PCIE_LTSSM_CONTROL_CAP);
> + ltssm_control_cap = ((ltssm_control_cap &
> + ~CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK) |
> + CDNS_PCIE_DETECT_QUIET_MIN_DELAY(delay));
> +
> + cdns_pcie_writel(pcie, CDNS_PCIE_LTSSM_CONTROL_CAP, ltssm_control_cap);
> +}
> +
The issue is not specific to only host mode.
Thanks
Kishon
> int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
> {
> struct device *dev = rc->pcie.dev;
> @@ -485,6 +499,10 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
> rc->device_id = 0xffff;
> of_property_read_u32(np, "device-id", &rc->device_id);
>
> + rc->detect_quiet_min_delay = 0;
> + of_property_read_u32(np, "detect-quiet-min-delay",
> + &rc->detect_quiet_min_delay);
> +
> pcie->reg_base = devm_platform_ioremap_resource_byname(pdev, "reg");
> if (IS_ERR(pcie->reg_base)) {
> dev_err(dev, "missing \"reg\"\n");
> @@ -497,6 +515,10 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
> return PTR_ERR(rc->cfg_base);
> rc->cfg_res = res;
>
> + /* Default Detect.Quiet state delay is 0 */
> + if (rc->detect_quiet_min_delay)
> + cdns_pcie_detect_quiet_min_delay_set(rc);
> +
> ret = cdns_pcie_start_link(pcie);
> if (ret) {
> dev_err(dev, "Failed to start link\n");
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index 254d2570f8c9..f2d3cca2c707 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -189,6 +189,14 @@
> /* AXI link down register */
> #define CDNS_PCIE_AT_LINKDOWN (CDNS_PCIE_AT_BASE + 0x0824)
>
> +/* LTSSM Capabilities register */
> +#define CDNS_PCIE_LTSSM_CONTROL_CAP (CDNS_PCIE_LM_BASE + 0x0054)
> +#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK GENMASK(2, 1)
> +#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY_SHIFT 1
> +#define CDNS_PCIE_DETECT_QUIET_MIN_DELAY(delay) \
> + (((delay) << CDNS_PCIE_DETECT_QUIET_MIN_DELAY_SHIFT) & \
> + CDNS_PCIE_DETECT_QUIET_MIN_DELAY_MASK)
> +
> enum cdns_pcie_rp_bar {
> RP_BAR_UNDEFINED = -1,
> RP_BAR0,
> @@ -289,6 +297,7 @@ struct cdns_pcie {
> * single function at a time
> * @vendor_id: PCI vendor ID
> * @device_id: PCI device ID
> + * @detect_quiet_min_delay: LTSSM Detect Quite state min. delay
> * @avail_ib_bar: Satus of RP_BAR0, RP_BAR1 and RP_NO_BAR if it's free or
> * available
> * @quirk_retrain_flag: Retrain link as quirk for PCIe Gen2
> @@ -299,6 +308,7 @@ struct cdns_pcie_rc {
> void __iomem *cfg_base;
> u32 vendor_id;
> u32 device_id;
> + u32 detect_quiet_min_delay;
> bool avail_ib_bar[CDNS_PCIE_RP_MAX_IB];
> bool quirk_retrain_flag;
> };
>