Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Quanyang Wang <quanyang.wang@windriver.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Sasha Levin <sashal@kernel.org>,
        dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org
Subject: [PATCH AUTOSEL 5.14 129/252] drm: xlnx: zynqmp_dpsub: Call pm_runtime_get_sync before setting pixel clock
Date:   Thu,  9 Sep 2021 07:39:03 -0400
Message-Id: <20210909114106.141462-129-sashal@kernel.org>
In-Reply-To: <20210909114106.141462-1-sashal@kernel.org>
References: <20210909114106.141462-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Quanyang Wang <quanyang.wang@windriver.com>

[ Upstream commit a19effb6dbe5bd1be77a6d68eba04dba8993ffeb ]

The Runtime PM subsystem will force the device "fd4a0000.zynqmp-display"
to enter suspend state while booting if the following conditions are met:
- the usage counter is zero (pm_runtime_get_sync hasn't been called yet)
- no 'active' children (no zynqmp-dp-snd-xx node under dpsub node)
- no other device in the same power domain (dpdma node has no
		"power-domains = <&zynqmp_firmware PD_DP>" property)

So there is a scenario as below:
1) DP device enters suspend state   <- call zynqmp_gpd_power_off
2) zynqmp_disp_crtc_setup_clock	    <- configurate register VPLL_FRAC_CFG
3) pm_runtime_get_sync		    <- call zynqmp_gpd_power_on and clear previous
				       VPLL_FRAC_CFG configuration
4) clk_prepare_enable(disp->pclk)   <- enable failed since VPLL_FRAC_CFG
				       configuration is corrupted

From above, we can see that pm_runtime_get_sync may clear register
VPLL_FRAC_CFG configuration and result the failure of clk enabling.
Putting pm_runtime_get_sync at the very beginning of the function
zynqmp_disp_crtc_atomic_enable can resolve this issue.

Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/xlnx/zynqmp_disp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xlnx/zynqmp_disp.c b/drivers/gpu/drm/xlnx/zynqmp_disp.c
index 109d627968ac..01c6ce7784dd 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_disp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_disp.c
@@ -1452,9 +1452,10 @@ zynqmp_disp_crtc_atomic_enable(struct drm_crtc *crtc,
 	struct drm_display_mode *adjusted_mode = &crtc->state->adjusted_mode;
 	int ret, vrefresh;
 
+	pm_runtime_get_sync(disp->dev);
+
 	zynqmp_disp_crtc_setup_clock(crtc, adjusted_mode);
 
-	pm_runtime_get_sync(disp->dev);
 	ret = clk_prepare_enable(disp->pclk);
 	if (ret) {
 		dev_err(disp->dev, "failed to enable a pixel clock\n");
-- 
2.30.2