gpu: nvgpu: filter frequencies only when required

the logic used for selecting frequencies from achievable frequencies
of the GPU clk is selecting one in a set of 8 frequencies.
This reduces the number of available frequencies when the number of
achievable frequencies is small. Change this implementation to choose
all frequencies when the achievable frequency list is small.

Bug 200381453

Change-Id: Ib280d7ccf9b75f88f6c7c6d2666f05e92a0343bd
Signed-off-by: Vishruth <vishruthj@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1753289
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 44 insertions, 15 deletions

diff --git a/drivers/gpu/nvgpu/os/linux/platform_gp10b_tegra.c b/drivers/gpu/nvgpu/os/linux/platform_gp10b_tegra.c
index cf18fd24..3fc216a1 100644
--- a/drivers/gpu/nvgpu/os/linux/platform_gp10b_tegra.c
+++ b/drivers/gpu/nvgpu/os/linux/platform_gp10b_tegra.c
@@ -50,6 +50,8 @@
 
 /* Select every GP10B_FREQ_SELECT_STEP'th frequency from h/w table */
 #define GP10B_FREQ_SELECT_STEP  8
+/* Allow limited set of frequencies to be available */
+#define GP10B_NUM_SUPPORTED_FREQS 15
 /* Max number of freq supported in h/w */
 #define GP10B_MAX_SUPPORTED_FREQS 120
 static unsigned long
@@ -343,33 +345,60 @@ int gp10b_clk_get_freqs(struct device *dev,
         struct gk20a *g = platform->g;
         unsigned long max_rate;
         unsigned long new_rate = 0, prev_rate = 0;
-        int i = 0, freq_counter = 0;
+        int i, freq_counter = 0;
+        int sel_freq_cnt;
+        unsigned long loc_freq_table[GP10B_MAX_SUPPORTED_FREQS];
 
         max_rate = clk_round_rate(platform->clk[0], (UINT_MAX - 1));
 
         /*
-         * Walk the h/w frequency table and only select
-         * GP10B_FREQ_SELECT_STEP'th frequencies and
-         * add MAX freq to last
+         * Walk the h/w frequency table and update the local table
          */
-        for (; i < GP10B_MAX_SUPPORTED_FREQS; ++i) {
+        for (i = 0; i < GP10B_MAX_SUPPORTED_FREQS; ++i) {
                 prev_rate = new_rate;
-                new_rate = clk_round_rate(platform->clk[0], prev_rate + 1);
-
-                if (i % GP10B_FREQ_SELECT_STEP == 0 ||
-                                new_rate == max_rate) {
-                        gp10b_freq_table[freq_counter++] = new_rate;
+                new_rate = clk_round_rate(platform->clk[0],
+                                                prev_rate + 1);
+                loc_freq_table[i] = new_rate;
+                if (new_rate == max_rate)
+                        break;
+        }
+        freq_counter = i;
+        WARN_ON(freq_counter == GP10B_MAX_SUPPORTED_FREQS);
 
-                        if (new_rate == max_rate)
-                                break;
+        /*
+         * If the number of achievable frequencies is less than or
+         * equal to GP10B_NUM_SUPPORTED_FREQS, select all frequencies
+         * else, select one out of every 8 frequencies
+         */
+        if (freq_counter <= GP10B_NUM_SUPPORTED_FREQS) {
+                for (sel_freq_cnt = 0; sel_freq_cnt < freq_counter; ++sel_freq_cnt)
+                        gp10b_freq_table[sel_freq_cnt] =
+                                        loc_freq_table[sel_freq_cnt];
+        } else {
+                /*
+                 * Walk the h/w frequency table and only select
+                 * GP10B_FREQ_SELECT_STEP'th frequencies and
+                 * add MAX freq to last
+                 */
+                sel_freq_cnt = 0;
+                for (i = 0; i < GP10B_MAX_SUPPORTED_FREQS; ++i) {
+                        new_rate = loc_freq_table[i];
+
+                        if (i % GP10B_FREQ_SELECT_STEP == 0 ||
+                                        new_rate == max_rate) {
+                                gp10b_freq_table[sel_freq_cnt++] =
+                                                        new_rate;
+
+                                if (new_rate == max_rate)
+                                        break;
+                        }
                 }
+                WARN_ON(sel_freq_cnt == GP10B_MAX_SUPPORTED_FREQS);
         }
 
-        WARN_ON(i == GP10B_MAX_SUPPORTED_FREQS);
-
         /* Fill freq table */
         *freqs = gp10b_freq_table;
-        *num_freqs = freq_counter;
+        *num_freqs = sel_freq_cnt;
 
         nvgpu_log_info(g, "min rate: %ld max rate: %ld num_of_freq %d\n",
                                 gp10b_freq_table[0], max_rate, *num_freqs);