Re: [PATCH 2/4] drm/msm: dsi: Use OPP API to set clk/perf state

From: Rajendra Nayak
Date: Thu Jul 02 2020 - 04:55:38 EST


On 7/1/2020 9:57 PM, Matthias Kaehlcke wrote:
On Tue, Jun 30, 2020 at 05:26:14PM +0530, Rajendra Nayak wrote:
On SDM845 DSI needs to express a perforamnce state

nit: performance

requirement on a power domain depending on the clock rates.
Use OPP table from DT to register with OPP framework and use
dev_pm_opp_set_rate() to set the clk/perf state.

Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/msm/dsi/dsi.h | 2 ++
drivers/gpu/drm/msm/dsi/dsi_cfg.c | 4 +--
drivers/gpu/drm/msm/dsi/dsi_host.c | 58 ++++++++++++++++++++++++++++++++++++++
3 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi.h b/drivers/gpu/drm/msm/dsi/dsi.h
index 4de771d..ba7583c 100644
--- a/drivers/gpu/drm/msm/dsi/dsi.h
+++ b/drivers/gpu/drm/msm/dsi/dsi.h
@@ -180,10 +180,12 @@ int msm_dsi_runtime_suspend(struct device *dev);
int msm_dsi_runtime_resume(struct device *dev);
int dsi_link_clk_set_rate_6g(struct msm_dsi_host *msm_host);
int dsi_link_clk_set_rate_v2(struct msm_dsi_host *msm_host);
+int dsi_link_clk_set_rate_6g_v2(struct msm_dsi_host *msm_host);
int dsi_link_clk_enable_6g(struct msm_dsi_host *msm_host);
int dsi_link_clk_enable_v2(struct msm_dsi_host *msm_host);
void dsi_link_clk_disable_6g(struct msm_dsi_host *msm_host);
void dsi_link_clk_disable_v2(struct msm_dsi_host *msm_host);
+void dsi_link_clk_disable_6g_v2(struct msm_dsi_host *msm_host);
int dsi_tx_buf_alloc_6g(struct msm_dsi_host *msm_host, int size);
int dsi_tx_buf_alloc_v2(struct msm_dsi_host *msm_host, int size);
void *dsi_tx_buf_get_6g(struct msm_dsi_host *msm_host);
diff --git a/drivers/gpu/drm/msm/dsi/dsi_cfg.c b/drivers/gpu/drm/msm/dsi/dsi_cfg.c
index 813d69d..773c4fe 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_cfg.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_cfg.c
@@ -210,9 +210,9 @@ static const struct msm_dsi_host_cfg_ops msm_dsi_6g_host_ops = {
};
static const struct msm_dsi_host_cfg_ops msm_dsi_6g_v2_host_ops = {
- .link_clk_set_rate = dsi_link_clk_set_rate_6g,
+ .link_clk_set_rate = dsi_link_clk_set_rate_6g_v2,
.link_clk_enable = dsi_link_clk_enable_6g,
- .link_clk_disable = dsi_link_clk_disable_6g,
+ .link_clk_disable = dsi_link_clk_disable_6g_v2,
.clk_init_ver = dsi_clk_init_6g_v2,
.tx_buf_alloc = dsi_tx_buf_alloc_6g,
.tx_buf_get = dsi_tx_buf_get_6g,
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 11ae5b8..890531c 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -14,6 +14,7 @@
#include <linux/of_graph.h>
#include <linux/of_irq.h>
#include <linux/pinctrl/consumer.h>
+#include <linux/pm_opp.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/spinlock.h>
@@ -111,6 +112,9 @@ struct msm_dsi_host {
struct clk *pixel_clk_src;
struct clk *byte_intf_clk;
+ struct opp_table *opp_table;
+ bool has_opp_table;
+
u32 byte_clk_rate;
u32 pixel_clk_rate;
u32 esc_clk_rate;
@@ -537,6 +541,38 @@ int dsi_link_clk_set_rate_6g(struct msm_dsi_host *msm_host)
return 0;
}
+int dsi_link_clk_set_rate_6g_v2(struct msm_dsi_host *msm_host)
+{
+ int ret;
+ struct device *dev = &msm_host->pdev->dev;
+
+ DBG("Set clk rates: pclk=%d, byteclk=%d",
+ msm_host->mode->clock, msm_host->byte_clk_rate);
+
+ ret = dev_pm_opp_set_rate(dev, msm_host->byte_clk_rate);
+ if (ret) {
+ pr_err("%s: dev_pm_opp_set_rate failed %d\n", __func__, ret);
+ return ret;
+ }
+
+ ret = clk_set_rate(msm_host->pixel_clk, msm_host->pixel_clk_rate);
+ if (ret) {
+ pr_err("%s: Failed to set rate pixel clk, %d\n", __func__, ret);
+ return ret;
+ }
+
+ if (msm_host->byte_intf_clk) {
+ ret = clk_set_rate(msm_host->byte_intf_clk,
+ msm_host->byte_clk_rate / 2);
+ if (ret) {
+ pr_err("%s: Failed to set rate byte intf clk, %d\n",
+ __func__, ret);
+ return ret;
+ }
+ }
+
+ return 0;
+}

xThis function is essentially the same as dsi_link_clk_set_rate_6g(),
except for the use of dev_pm_opp_set_rate() instead of clk_set_rate().

IIUC dev_pm_opp_set_rate() just calls clk_set_rate() if the device has
no OPP table. If that's correct you could just call dev_pm_opp_set_rate()
in dsi_link_clk_set_rate_6g().

/*
* For IO devices which require an OPP on some platforms/SoCs
* while just needing to scale the clock on some others
* we look for empty OPP tables with just a clock handle and
* scale only the clk. This makes dev_pm_opp_set_rate()
* equivalent to a clk_set_rate()
*/
if (!_get_opp_count(opp_table)) {
ret = _generic_set_opp_clk_only(dev, clk, freq);
goto put_opp_table;
}

ah, thats right, I think I had this code from before that support got
added to dev_pm_opp_set_rate() and I just did not update this driver to
make use of it. Thanks for catching it, I will fix it up and repost soon.


https://elixir.bootlin.com/linux/v5.7.6/source/drivers/opp/core.c#L855

int dsi_link_clk_enable_6g(struct msm_dsi_host *msm_host)
{
@@ -665,6 +701,13 @@ void dsi_link_clk_disable_6g(struct msm_dsi_host *msm_host)
clk_disable_unprepare(msm_host->byte_clk);
}
+void dsi_link_clk_disable_6g_v2(struct msm_dsi_host *msm_host)
+{
+ /* Drop the performance state vote */
+ dev_pm_opp_set_rate(&msm_host->pdev->dev, 0);

Couldn't you just do this in dsi_link_clk_disable_6g() ?

yes, looks like I can, I'll get rid of both of these additional functions.

thanks,
Rajendra

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