This patch adds common helpers to issue power commands, poll
transitions, and validate domain state, then wires them into the L2
on/off paths.

The L2 power-on sequence now delegates control of the SHADER and TILER
domains to the MCU when allowed, while the L2 itself is never delegated.
On power-off, dependent domains beneath the L2 are checked, and if
necessary, retracted and powered down to maintain proper domain
ordering.

Signed-off-by: Karunika Choo <[email protected]>
---
 drivers/gpu/drm/panthor/panthor_pwr.c | 390 +++++++++++++++++++++++++-
 1 file changed, 388 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_pwr.c 
b/drivers/gpu/drm/panthor/panthor_pwr.c
index d07ad5b7953a..594181aba847 100644
--- a/drivers/gpu/drm/panthor/panthor_pwr.c
+++ b/drivers/gpu/drm/panthor/panthor_pwr.c
@@ -23,6 +23,14 @@
         PWR_IRQ_COMMAND_NOT_ALLOWED | \
         PWR_IRQ_COMMAND_INVALID)
 
+#define PWR_ALL_CORES_MASK             GENMASK(63, 0)
+
+#define PWR_DOMAIN_MAX_BITS            16
+
+#define PWR_TRANSITION_TIMEOUT_US      2000000
+
+#define PWR_RETRACT_TIMEOUT_US         2000
+
 /**
  * struct panthor_pwr - PWR_CONTROL block management data.
  */
@@ -59,6 +67,302 @@ static void panthor_pwr_irq_handler(struct panthor_device 
*ptdev, u32 status)
 }
 PANTHOR_IRQ_HANDLER(pwr, PWR, panthor_pwr_irq_handler);
 
+static u64 panthor_pwr_read_status(struct panthor_device *ptdev)
+{
+       return gpu_read64(ptdev, PWR_STATUS);
+}
+
+static void panthor_pwr_write_command(struct panthor_device *ptdev, u32 
command, u64 args)
+{
+       if (args)
+               gpu_write64(ptdev, PWR_CMDARG, args);
+
+       gpu_write(ptdev, PWR_COMMAND, command);
+}
+
+static const char *get_domain_name(u8 domain)
+{
+       switch (domain) {
+       case PWR_COMMAND_DOMAIN_L2:
+               return "L2";
+       case PWR_COMMAND_DOMAIN_TILER:
+               return "Tiler";
+       case PWR_COMMAND_DOMAIN_SHADER:
+               return "Shader";
+       case PWR_COMMAND_DOMAIN_BASE:
+               return "Base";
+       case PWR_COMMAND_DOMAIN_STACK:
+               return "Stack";
+       }
+       return "Unknown";
+}
+
+static u32 get_domain_base(u8 domain)
+{
+       switch (domain) {
+       case PWR_COMMAND_DOMAIN_L2:
+               return PWR_L2_PRESENT;
+       case PWR_COMMAND_DOMAIN_TILER:
+               return PWR_TILER_PRESENT;
+       case PWR_COMMAND_DOMAIN_SHADER:
+               return PWR_SHADER_PRESENT;
+       case PWR_COMMAND_DOMAIN_BASE:
+               return PWR_BASE_PRESENT;
+       case PWR_COMMAND_DOMAIN_STACK:
+               return PWR_STACK_PRESENT;
+       }
+       return 0;
+}
+
+static u32 get_domain_ready_reg(u32 domain)
+{
+       return get_domain_base(domain) + (PWR_L2_READY - PWR_L2_PRESENT);
+}
+
+static u32 get_domain_pwrtrans_reg(u32 domain)
+{
+       return get_domain_base(domain) + (PWR_L2_PWRTRANS - PWR_L2_PRESENT);
+}
+
+static bool is_valid_domain(u32 domain)
+{
+       return get_domain_base(domain) != 0;
+}
+
+static bool has_rtu(struct panthor_device *ptdev)
+{
+       return ptdev->gpu_info.gpu_features & GPU_FEATURES_RAY_TRAVERSAL;
+}
+
+static u8 get_domain_subdomain(struct panthor_device *ptdev, u32 domain)
+{
+       if ((domain == PWR_COMMAND_DOMAIN_SHADER) && has_rtu(ptdev))
+               return PWR_COMMAND_SUBDOMAIN_RTU;
+
+       return 0;
+}
+
+static int panthor_pwr_domain_wait_transition(struct panthor_device *ptdev, 
u32 domain,
+                                             u32 timeout_us)
+{
+       u32 pwrtrans_reg = get_domain_pwrtrans_reg(domain);
+       u64 val;
+       int ret = 0;
+
+       ret = gpu_read64_poll_timeout(ptdev, pwrtrans_reg, val,
+                                     !(PWR_ALL_CORES_MASK & val), 100,
+                                     timeout_us);
+       if (ret) {
+               drm_err(&ptdev->base, "%s domain power in transition, 
pwrtrans(0x%llx)",
+                       get_domain_name(domain), val);
+               return ret;
+       }
+
+       return 0;
+}
+
+static void panthor_pwr_info_show(struct panthor_device *ptdev)
+{
+       drm_info(&ptdev->base, "GPU_FEATURES:    0x%016llx", 
ptdev->gpu_info.gpu_features);
+       drm_info(&ptdev->base, "PWR_STATUS:      0x%016llx", gpu_read64(ptdev, 
PWR_STATUS));
+       drm_info(&ptdev->base, "L2_PRESENT:      0x%016llx", gpu_read64(ptdev, 
PWR_L2_PRESENT));
+       drm_info(&ptdev->base, "L2_PWRTRANS:     0x%016llx", gpu_read64(ptdev, 
PWR_L2_PWRTRANS));
+       drm_info(&ptdev->base, "L2_READY:        0x%016llx", gpu_read64(ptdev, 
PWR_L2_READY));
+       drm_info(&ptdev->base, "TILER_PRESENT:   0x%016llx", gpu_read64(ptdev, 
PWR_TILER_PRESENT));
+       drm_info(&ptdev->base, "TILER_PWRTRANS:  0x%016llx", gpu_read64(ptdev, 
PWR_TILER_PWRTRANS));
+       drm_info(&ptdev->base, "TILER_READY:     0x%016llx", gpu_read64(ptdev, 
PWR_TILER_READY));
+       drm_info(&ptdev->base, "SHADER_PRESENT:  0x%016llx", gpu_read64(ptdev, 
PWR_SHADER_PRESENT));
+       drm_info(&ptdev->base, "SHADER_PWRTRANS: 0x%016llx",
+                gpu_read64(ptdev, PWR_SHADER_PWRTRANS));
+       drm_info(&ptdev->base, "SHADER_READY:    0x%016llx", gpu_read64(ptdev, 
PWR_SHADER_READY));
+}
+
+static int panthor_pwr_domain_transition(struct panthor_device *ptdev, u32 
cmd, u32 domain,
+                                        u64 mask, u32 timeout_us)
+{
+       u32 ready_reg = get_domain_ready_reg(domain);
+       u32 pwr_cmd = PWR_COMMAND_DEF(cmd, domain, get_domain_subdomain(ptdev, 
domain));
+       u64 expected_val = cmd == PWR_COMMAND_POWER_DOWN ? 0 : mask;
+       u64 val;
+       int ret = 0;
+
+       if (!is_valid_domain(domain))
+               return -EINVAL;
+
+       if (cmd != PWR_COMMAND_POWER_DOWN && cmd != PWR_COMMAND_POWER_UP) {
+               drm_err(&ptdev->base, "Invalid power domain transition command 
(0x%x)", cmd);
+               return -EINVAL;
+       }
+
+       ret = panthor_pwr_domain_wait_transition(ptdev, domain, timeout_us);
+       if (ret)
+               return ret;
+
+       /* domain already in target state, return early */
+       if ((gpu_read64(ptdev, ready_reg) & mask) == expected_val)
+               return 0;
+
+       panthor_pwr_write_command(ptdev, pwr_cmd, mask);
+
+       ret = gpu_read64_poll_timeout(ptdev, ready_reg, val, (mask & val) == 
expected_val, 100,
+                                     timeout_us);
+       if (ret) {
+               drm_err(&ptdev->base, "timeout waiting on %s power %s, 
cmd(0x%x), arg(0x%llx)",
+                       get_domain_name(domain), cmd == PWR_COMMAND_POWER_DOWN 
? "down" : "up",
+                       pwr_cmd, mask);
+               panthor_pwr_info_show(ptdev);
+               return ret;
+       }
+
+       return 0;
+}
+
+#define panthor_pwr_domain_power_off(__ptdev, __domain, __mask, __timeout_us)  
          \
+       panthor_pwr_domain_transition(__ptdev, PWR_COMMAND_POWER_DOWN, 
__domain, __mask, \
+                                     __timeout_us)
+
+#define panthor_pwr_domain_power_on(__ptdev, __domain, __mask, __timeout_us) \
+       panthor_pwr_domain_transition(__ptdev, PWR_COMMAND_POWER_UP, __domain, 
__mask, __timeout_us)
+
+/**
+ * retract_domain() - Retract control of a domain from MCU
+ * @ptdev: Device.
+ * @domain: Domain to retract the control
+ *
+ * Retracting L2 domain is not expected since it won't be delegated.
+ *
+ * Return: 0 on success or retracted already.
+ *         -EPERM if domain is L2.
+ *         A negative error code otherwise.
+ */
+static int retract_domain(struct panthor_device *ptdev, u32 domain)
+{
+       const u32 pwr_cmd = PWR_COMMAND_DEF(PWR_COMMAND_RETRACT, domain, 0);
+       const u32 pwr_status_reg = panthor_pwr_read_status(ptdev);
+       const u32 delegated_mask = PWR_STATUS_DOMAIN_DELEGATED(domain);
+       const u32 allow_mask = PWR_STATUS_DOMAIN_ALLOWED(domain);
+       u64 val;
+       int ret;
+
+       if (WARN_ON(domain == PWR_COMMAND_DOMAIN_L2))
+               return -EINVAL;
+
+       if (WARN_ON(pwr_status_reg & 
PWR_STATUS_DOMAIN_DELEGATED(PWR_COMMAND_DOMAIN_L2)))
+               return -EPERM;
+
+       if (!(pwr_status_reg & delegated_mask)) {
+               drm_dbg(&ptdev->base, "%s domain already retracted",
+                       get_domain_name(domain));
+               return 0;
+       }
+
+       ret = gpu_read64_poll_timeout(ptdev, PWR_STATUS, val,
+                                     !(PWR_STATUS_RETRACT_PENDING & val), 0,
+                                     PWR_RETRACT_TIMEOUT_US);
+       if (ret) {
+               drm_err(&ptdev->base, "%s domain retract pending",
+                       get_domain_name(domain));
+               return ret;
+       }
+
+       panthor_pwr_write_command(ptdev, pwr_cmd, 0);
+
+       /*
+        * On successful retraction
+        * allow-flag will be set with delegated-flag being cleared.
+        */
+       ret = gpu_read64_poll_timeout(ptdev, PWR_STATUS, val,
+                                     ((delegated_mask | allow_mask) & val) == 
allow_mask,
+                                     10, PWR_TRANSITION_TIMEOUT_US);
+       if (ret) {
+               drm_err(&ptdev->base, "Retracting %s domain timeout, cmd(0x%x)",
+                       get_domain_name(domain), pwr_cmd);
+               return ret;
+       }
+
+       return 0;
+}
+
+/**
+ * delegate_domain() - Delegate control of a domain to MCU
+ * @ptdev: Device.
+ * @domain: Domain to delegate the control
+ *
+ * Delegating L2 domain is prohibited.
+ *
+ * Return:
+ * *       0 on success or delegated already.
+ * *       -EPERM if domain is L2.
+ * *       A negative error code otherwise.
+ */
+static int delegate_domain(struct panthor_device *ptdev, u32 domain)
+{
+       const u32 pwr_cmd = PWR_COMMAND_DEF(PWR_COMMAND_DELEGATE, domain, 0);
+       const u32 pwr_status_reg = panthor_pwr_read_status(ptdev);
+       const u32 pwrtrans_reg = get_domain_pwrtrans_reg(domain);
+       const u32 allow_mask = PWR_STATUS_DOMAIN_ALLOWED(domain);
+       const u32 delegated_mask = PWR_STATUS_DOMAIN_DELEGATED(domain);
+       u64 val;
+       int ret;
+
+       if (WARN_ON_ONCE(domain == PWR_COMMAND_DOMAIN_L2))
+               return -EINVAL;
+
+       if (pwr_status_reg & delegated_mask) {
+               drm_dbg(&ptdev->base, "%s domain already delegated",
+                       get_domain_name(domain));
+               return 0;
+       }
+
+       /* Check if the command is allowed before delegating. */
+       if (unlikely(!(pwr_status_reg & allow_mask))) {
+               drm_warn(&ptdev->base, "Delegating %s domain not allowed",
+                        get_domain_name(domain));
+               return -EPERM;
+       }
+
+       if (unlikely(gpu_read64(ptdev, pwrtrans_reg))) {
+               drm_warn(&ptdev->base, "%s domain power in transition",
+                        get_domain_name(domain));
+               return -EPERM;
+       }
+
+       panthor_pwr_write_command(ptdev, pwr_cmd, 0);
+
+       /*
+        * On successful delegation
+        * allow-flag will be cleared with delegated-flag being set.
+        */
+       ret = gpu_read64_poll_timeout(ptdev, PWR_STATUS, val,
+                                     ((delegated_mask | allow_mask) & val) == 
delegated_mask,
+                                     10, PWR_TRANSITION_TIMEOUT_US);
+       if (ret) {
+               drm_err(&ptdev->base, "Delegating %s domain timeout, cmd(0x%x)",
+                       get_domain_name(domain), pwr_cmd);
+               return ret;
+       }
+
+       return 0;
+}
+
+static int panthor_pwr_delegate_domains(struct panthor_device *ptdev)
+{
+       int ret;
+
+       if (!ptdev->pwr)
+               return 0;
+
+       ret = delegate_domain(ptdev, PWR_COMMAND_DOMAIN_SHADER);
+       if (ret)
+               return ret;
+
+       ret = delegate_domain(ptdev, PWR_COMMAND_DOMAIN_TILER);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
 void panthor_pwr_unplug(struct panthor_device *ptdev)
 {
        unsigned long flags;
@@ -110,12 +414,94 @@ int panthor_pwr_reset_soft(struct panthor_device *ptdev)
 
 int panthor_pwr_l2_power_off(struct panthor_device *ptdev)
 {
-       return 0;
+       const u32 l2_allow_mask = 
PWR_STATUS_DOMAIN_ALLOWED(PWR_COMMAND_DOMAIN_L2);
+       const u32 l2_pwrtrans_reg = 
get_domain_pwrtrans_reg(PWR_COMMAND_DOMAIN_L2);
+       unsigned long child_domain_mask = {
+               BIT(PWR_COMMAND_DOMAIN_SHADER) |
+               BIT(PWR_COMMAND_DOMAIN_TILER)
+       };
+       u32 pwr_status, child_domain;
+       int ret = 0;
+
+       if (unlikely(!ptdev->pwr))
+               return -ENODEV;
+
+       pwr_status = panthor_pwr_read_status(ptdev);
+
+       /* Abort if L2 power off constraints are not satisfied */
+       if (!(pwr_status & l2_allow_mask)) {
+               drm_warn(&ptdev->base, "Power off L2 domain not allowed");
+               return 0;
+       }
+
+       if (gpu_read64(ptdev, l2_pwrtrans_reg)) {
+               drm_warn(&ptdev->base, "L2 Power in transition");
+               return 0;
+       }
+
+       /* It is expected that when halting the MCU, it would power down its
+        * delegated domains. However, an unresponsive or hung MCU may not do
+        * so, which is why we need to check and retract the domains back into
+        * host control to be powered down before powering down the L2.
+        */
+       for_each_set_bit(child_domain, &child_domain_mask, PWR_DOMAIN_MAX_BITS) 
{
+               u64 domain_ready = gpu_read64(ptdev, 
get_domain_ready_reg(child_domain));
+
+               if (domain_ready && (pwr_status & 
PWR_STATUS_DOMAIN_DELEGATED(child_domain))) {
+                       drm_warn(&ptdev->base,
+                                "L2 power off: Delegated %s domain not powered 
down by MCU",
+                                get_domain_name(child_domain));
+                       ret = retract_domain(ptdev, child_domain);
+                       if (ret) {
+                               drm_err(&ptdev->base, "Failed to retract %s 
domain",
+                                       get_domain_name(child_domain));
+                               panthor_pwr_info_show(ptdev);
+                               return ret;
+                       }
+               }
+
+               ret = panthor_pwr_domain_power_off(ptdev, child_domain, 
domain_ready,
+                                                  PWR_TRANSITION_TIMEOUT_US);
+               if (ret)
+                       return ret;
+       }
+
+       return panthor_pwr_domain_power_off(ptdev, PWR_COMMAND_DOMAIN_L2,
+                                           ptdev->gpu_info.l2_present,
+                                           PWR_TRANSITION_TIMEOUT_US);
 }
 
 int panthor_pwr_l2_power_on(struct panthor_device *ptdev)
 {
-       return 0;
+       const u32 pwr_status = panthor_pwr_read_status(ptdev);
+       const u32 l2_allow_mask = 
PWR_STATUS_DOMAIN_ALLOWED(PWR_COMMAND_DOMAIN_L2);
+       const u32 l2_pwrtrans_reg = 
get_domain_pwrtrans_reg(PWR_COMMAND_DOMAIN_L2);
+       int ret;
+
+       if (!ptdev->pwr)
+               return 0;
+
+       if ((pwr_status & l2_allow_mask) == 0) {
+               drm_warn(&ptdev->base, "Power on L2 domain not allowed");
+               return -EPERM;
+       }
+
+       if (gpu_read64(ptdev, l2_pwrtrans_reg)) {
+               drm_warn(&ptdev->base, "L2 Power is in transition");
+               return -EINVAL;
+       }
+
+       ret = panthor_pwr_domain_power_on(ptdev, PWR_COMMAND_DOMAIN_L2,
+                                         ptdev->gpu_info.l2_present,
+                                         PWR_TRANSITION_TIMEOUT_US);
+       if (ret)
+               return ret;
+
+       /* Delegate control of the shader and tiler power domains to the MCU as
+        * it can better manage which shader/tiler cores need to be powered up
+        * or can be powered down based on currently running jobs.
+        */
+       return panthor_pwr_delegate_domains(ptdev);
 }
 
 void panthor_pwr_suspend(struct panthor_device *ptdev)
-- 
2.49.0

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