linux-kernel - [PATCH] Revert "firmware: arm_scmi: Add clock management to the SCMI power domain"

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Date:   Mon, 19 Sep 2022 14:20:33 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>,
        Cristian Marussi <cristian.marussi@....com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Peng Fan <peng.fan@....com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Dien Pham <dien.pham.ry@...esas.com>,
        Gaku Inami <gaku.inami.xh@...esas.com>,
        Nicolas Pitre <npitre@...libre.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH] Revert "firmware: arm_scmi: Add clock management to the SCMI power domain"

This reverts commit a3b884cef873 ("firmware: arm_scmi: Add clock management
to the SCMI power domain").

Using the GENPD_FLAG_PM_CLK tells genpd to gate/ungate the consumer
device's clock(s) during runtime suspend/resume through the PM clock API.
More precisely, in genpd_runtime_resume() the clock(s) for the consumer
device would become ungated prior to the driver-level ->runtime_resume()
callbacks gets invoked.

This behaviour isn't a good fit for all platforms/drivers. For example, a
driver may need to make some preparations of its device in its
->runtime_resume() callback, like calling clk_set_rate() before the
clock(s) should be ungated. In these cases, it's easier to let the clock(s)
to be managed solely by the driver, rather than at the PM domain level.

For these reasons, let's drop the use GENPD_FLAG_PM_CLK for the SCMI PM
domain, as to enable it to be more easily adopted across ARM platforms.

Fixes: a3b884cef873 ("firmware: arm_scmi: Add clock management to the SCMI power domain")
Cc: Nicolas Pitre <npitre@...libre.com>
Cc: stable@...r.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---

To get some more background to $subject patch, please have a look at the
lore-link below.

https://lore.kernel.org/all/DU0PR04MB94173B45A2CFEE3BF1BD313A88409@DU0PR04MB9417.eurprd04.prod.outlook.com/

Kind regards
Ulf Hansson

---
 drivers/firmware/arm_scmi/scmi_pm_domain.c | 26 ----------------------
 1 file changed, 26 deletions(-)

diff --git a/drivers/firmware/arm_scmi/scmi_pm_domain.c b/drivers/firmware/arm_scmi/scmi_pm_domain.c
index 581d34c95769..d5dee625de78 100644
--- a/drivers/firmware/arm_scmi/scmi_pm_domain.c
+++ b/drivers/firmware/arm_scmi/scmi_pm_domain.c
@@ -8,7 +8,6 @@
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.h>
-#include <linux/pm_clock.h>
 #include <linux/pm_domain.h>
 #include <linux/scmi_protocol.h>
 
@@ -53,27 +52,6 @@ static int scmi_pd_power_off(struct generic_pm_domain *domain)
 	return scmi_pd_power(domain, false);
 }
 
-static int scmi_pd_attach_dev(struct generic_pm_domain *pd, struct device *dev)
-{
-	int ret;
-
-	ret = pm_clk_create(dev);
-	if (ret)
-		return ret;
-
-	ret = of_pm_clk_add_clks(dev);
-	if (ret >= 0)
-		return 0;
-
-	pm_clk_destroy(dev);
-	return ret;
-}
-
-static void scmi_pd_detach_dev(struct generic_pm_domain *pd, struct device *dev)
-{
-	pm_clk_destroy(dev);
-}
-
 static int scmi_pm_domain_probe(struct scmi_device *sdev)
 {
 	int num_domains, i;
@@ -124,10 +102,6 @@ static int scmi_pm_domain_probe(struct scmi_device *sdev)
 		scmi_pd->genpd.name = scmi_pd->name;
 		scmi_pd->genpd.power_off = scmi_pd_power_off;
 		scmi_pd->genpd.power_on = scmi_pd_power_on;
-		scmi_pd->genpd.attach_dev = scmi_pd_attach_dev;
-		scmi_pd->genpd.detach_dev = scmi_pd_detach_dev;
-		scmi_pd->genpd.flags = GENPD_FLAG_PM_CLK |
-				       GENPD_FLAG_ACTIVE_WAKEUP;
 
 		pm_genpd_init(&scmi_pd->genpd, NULL,
 			      state == SCMI_POWER_STATE_GENERIC_OFF);
-- 
2.34.1