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gpu: nvgpu: gp10b: cache gpu clk rate

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Cache the rate used in clk_set_rate().
Return that cached rate on clk_get_rate(), don't read from hardware.
This cached rate is used to avoid duplicate requests to clk_set_rate().

Motivation is to support multiple governors for gpu clk.
Reading clock from hardware is unreliable in multi-governor situation.
Relying on hardware clock value could mislead the kernel gpu governor
in its scaling calculations.

Bug 2051688

Change-Id: I116b0ef73c51121b57ef36d08b6c67f49fdbf656
Signed-off-by: Arun Kannan <akannan@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1662759
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
This commit is contained in:
Arun Kannan
2018-02-15 11:57:57 -08:00
committed by mobile promotions
parent ac40d082e8
commit 7f819a9ba7
2 changed files with 15 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/gpu/nvgpu/gk20a/platform_gk20a.h
View File

@@ -55,6 +55,8 @@ struct gk20a_platform {
/* Should be populated at probe. */
bool can_elpg;
unsigned long cached_rate;
/* Should be populated at probe. */
bool has_syncpoints;
/* Debugfs knob for forcing syncpt support off in runtime. */

16
drivers/gpu/nvgpu/gp10b/platform_gp10b_tegra.c
View File

@@ -53,11 +53,13 @@ gp10b_freq_table[GP10B_MAX_SUPPORTED_FREQS / GP10B_FREQ_SELECT_STEP];
#define EMC_BW_RATIO (TEGRA_GP10B_BW_PER_FREQ / TEGRA_DDR4_BW_PER_FREQ)
#define GPCCLK_INIT_RATE 1000000000
static struct {
char *name;
unsigned long default_rate;
} tegra_gp10b_clocks[] = {
{"gpu", 1000000000},
{"gpu", GPCCLK_INIT_RATE},
{"gpu_sys", 204000000} };
static void gr_gp10b_remove_sysfs(struct device *dev);
@@ -335,7 +337,7 @@ static unsigned long gp10b_get_clk_rate(struct device *dev)
{
struct gk20a_platform *platform = gk20a_get_platform(dev);
return clk_get_rate(platform->clk[0]);
return platform->cached_rate;
}
@@ -357,8 +359,14 @@ static long gp10b_round_clk_rate(struct device *dev, unsigned long rate)
static int gp10b_set_clk_rate(struct device *dev, unsigned long rate)
{
struct gk20a_platform *platform = gk20a_get_platform(dev);
int ret;
return clk_set_rate(platform->clk[0], rate);
ret = clk_set_rate(platform->clk[0], rate);
if (!ret)
platform->cached_rate = rate;
return ret;
}
static int gp10b_clk_get_freqs(struct device *dev,
@@ -416,6 +424,8 @@ struct gk20a_platform gp10b_tegra_platform = {
.enable_elcg = true,
.enable_aelpg = true,
.cached_rate = GPCCLK_INIT_RATE,
/* ptimer src frequency in hz*/
.ptimer_src_freq = 31250000,