linux-kernel - [PATCH v2] drivers: soc: xilinx: Call InitFinalize from late_initcall

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Message-Id: <1599693000-25641-1-git-send-email-amit.sunil.dhamne@xilinx.com>
Date:   Wed,  9 Sep 2020 16:10:00 -0700
From:   Amit Sunil Dhamne <amit.sunil.dhamne@...inx.com>
To:     ard.biesheuvel@...aro.org, mingo@...nel.org,
        gregkh@...uxfoundation.org, matt@...eblueprint.co.uk,
        sudeep.holla@....com, hkallweit1@...il.com, keescook@...omium.org,
        dmitry.torokhov@...il.com, michal.simek@...inx.com
Cc:     rajanv@...inx.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, tejasp@...inx.com, jollys@...inx.com,
        Rajan Vaja <rajan.vaja@...inx.com>,
        Amit Sunil Dhamne <amit.sunil.dhamne@...inx.com>
Subject: [PATCH v2] drivers: soc: xilinx: Call InitFinalize from late_initcall_sync instead of probe

From: Rajan Vaja <rajan.vaja@...inx.com>

Initially all devices are in power up state. Firmware expect that
processor should call InitFinalize API once it have requested devices
which are required so that it can turn off all unused devices and
save power. From Linux, PM driver calls InitFinalize to inform the
firmware that it can power down the unused devices. Upon
InitFinalize() call firmware power downs all unused devices.

There are chances that PM driver is probed along with or before other
device drivers. So in that case some of the devices may not be
requested from firmware which is done by genpd driver. Due to that
firmware will consider those devices as unused and firmware will power
down those devices. Later when any device driver is probed, genpd
driver will ask firmware to power up that device using request node
API. So for those devices, power transition will be like on->off->on
which creates unnecessary power glitch to those devices.

To avoid such unnecessary power transitions and as ideal behavior
InitFinalize should be called after all drivers are probed. So call
InitFinalize from late_initcall_sync.

Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
Signed-off-by: Amit Sunil Dhamne <amit.sunil.dhamne@...inx.com>
---
Changes in v2:
 - Check for compatible string for zynqmp or versal platform before
   calling init finalize.
---
 drivers/soc/xilinx/zynqmp_power.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/xilinx/zynqmp_power.c b/drivers/soc/xilinx/zynqmp_power.c
index 31ff49f..22d2d2e 100644
--- a/drivers/soc/xilinx/zynqmp_power.c
+++ b/drivers/soc/xilinx/zynqmp_power.c
@@ -178,7 +178,6 @@ static int zynqmp_pm_probe(struct platform_device *pdev)
        u32 pm_api_version;
        struct mbox_client *client;

-       zynqmp_pm_init_finalize();
        zynqmp_pm_get_api_version(&pm_api_version);

        /* Check PM API version number */
@@ -246,6 +245,23 @@ static int zynqmp_pm_remove(struct platform_device *pdev)
        return 0;
 }

+static int __init do_init_finalize(void)
+{
+       struct device_node *np;
+
+       np = of_find_compatible_node(NULL, NULL, "xlnx,zynqmp");
+       if (!np) {
+               np = of_find_compatible_node(NULL, NULL, "xlnx,versal");
+               if (!np)
+                       return 0;
+       }
+       of_node_put(np);
+
+       return zynqmp_pm_init_finalize();
+}
+
+late_initcall_sync(do_init_finalize);
+
 static const struct of_device_id pm_of_match[] = {
        { .compatible = "xlnx,zynqmp-power", },
        { /* end of table */ },
--
2.7.4

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