[PATCH v1 7/7] drm/vc4: Make sure we don't end up with a core clock too high

[Maxime Ripard]

Following the clock rate range improvements to the clock framework,
trying to set a disjoint range on a clock will now result in an error.

Thus, we can't set a minimum rate higher than the maximum reported by
the firmware, or clk_set_min_rate() will fail.

Thus we need to clamp the rate we are about to ask for to the maximum
rate possible on that clock.

Signed-off-by: Maxime Ripard <max...@cerno.tech>

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index b45dcdfd7306..4794e7235bb0 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -22,6 +22,8 @@
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_vblank.h>
 
+#include <soc/bcm2835/raspberrypi-clocks.h>
+
 #include "vc4_drv.h"
 #include "vc4_regs.h"
 
@@ -354,6 +356,7 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state 
*state)
        struct vc4_hvs_state *new_hvs_state;
        struct drm_crtc *crtc;
        struct vc4_hvs_state *old_hvs_state;
+       unsigned long max_clock_rate;
        unsigned int channel;
        int i;
 
@@ -394,11 +397,12 @@ static void vc4_atomic_commit_tail(struct 
drm_atomic_state *state)
                old_hvs_state->fifo_state[channel].pending_commit = NULL;
        }
 
+       max_clock_rate = rpi_firmware_clk_get_max_rate(hvs->core_clk);
        if (vc4->is_vc5) {
                unsigned long state_rate = max(old_hvs_state->core_clock_rate,
                                               new_hvs_state->core_clock_rate);
-               unsigned long core_rate = max_t(unsigned long,
-                                               500000000, state_rate);
+               unsigned long core_rate = clamp_t(unsigned long, state_rate,
+                                                 500000000, max_clock_rate);
 
                drm_dbg(dev, "Raising the core clock at %lu Hz\n", core_rate);
 
@@ -432,14 +436,17 @@ static void vc4_atomic_commit_tail(struct 
drm_atomic_state *state)
        drm_atomic_helper_cleanup_planes(dev, state);
 
        if (vc4->is_vc5) {
-               drm_dbg(dev, "Running the core clock at %lu Hz\n",
-                       new_hvs_state->core_clock_rate);
+               unsigned long core_rate = min_t(unsigned long,
+                                              max_clock_rate,
+                                              new_hvs_state->core_clock_rate);
+
+               drm_dbg(dev, "Running the core clock at %lu Hz\n", core_rate);
 
                /*
                 * Request a clock rate based on the current HVS
                 * requirements.
                 */
-               WARN_ON(clk_set_min_rate(hvs->core_clk, 
new_hvs_state->core_clock_rate));
+               WARN_ON(clk_set_min_rate(hvs->core_clk, core_rate));
 
                drm_dbg(dev, "Core clock actual rate: %lu Hz\n",
                        clk_get_rate(hvs->core_clk));

-- 
b4 0.10.0-dev-a76f5