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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Yongqin Liu <yongqin.liu@linaro.org>,
        Tony Lindgren <tony@atomide.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 093/221] soc: ti: omap-prm: Fix occasional abort on reset deassert for dra7 iva
Date:   Mon, 29 Mar 2021 09:57:04 +0200
Message-Id: <20210329075632.304887135@linuxfoundation.org>
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References: <20210329075629.172032742@linuxfoundation.org>
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From: Tony Lindgren <tony@atomide.com>

[ Upstream commit effe89e40037038db7711bdab5d3401fe297d72c ]

On reset deassert, we must wait a bit after the rstst bit change before
we allow clockdomain autoidle again. Otherwise we get the following oops
sometimes on dra7 with iva:

Unhandled fault: imprecise external abort (0x1406) at 0x00000000
44000000.ocp:L3 Standard Error: MASTER MPU TARGET IVA_CONFIG (Read Link):
At Address: 0x0005A410 : Data Access in User mode during Functional access
Internal error: : 1406 [#1] SMP ARM
...
(sysc_write_sysconfig) from [<c0782cb0>] (sysc_enable_module+0xcc/0x260)
(sysc_enable_module) from [<c0782f0c>] (sysc_runtime_resume+0xc8/0x174)
(sysc_runtime_resume) from [<c0a3e1ac>] (genpd_runtime_resume+0x94/0x224)
(genpd_runtime_resume) from [<c0a33f0c>] (__rpm_callback+0xd8/0x180)

It is unclear what all devices this might affect, but presumably other
devices with the rstst bit too can be affected. So let's just enable the
delay for all the devices with rstst bit for now. Later on we may want to
limit the list to the know affected devices if needed.

Fixes: d30cd83f6853 ("soc: ti: omap-prm: add support for denying idle for reset clockdomain")
Reported-by: Yongqin Liu <yongqin.liu@linaro.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/soc/ti/omap_prm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/ti/omap_prm.c b/drivers/soc/ti/omap_prm.c
index c8b14b3a171f..fb067b5e4a97 100644
--- a/drivers/soc/ti/omap_prm.c
+++ b/drivers/soc/ti/omap_prm.c
@@ -522,8 +522,12 @@ static int omap_reset_deassert(struct reset_controller_dev *rcdev,
 		       reset->prm->data->name, id);
 
 exit:
-	if (reset->clkdm)
+	if (reset->clkdm) {
+		/* At least dra7 iva needs a delay before clkdm idle */
+		if (has_rstst)
+			udelay(1);
 		pdata->clkdm_allow_idle(reset->clkdm);
+	}
 
 	return ret;
 }
-- 
2.30.1