linux-kernel - [PATCH] bus: ti-sysc: Use fsleep() instead of usleep_range() in sysc

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Message-Id: <20230821-fix-ti-sysc-reset-v1-1-5a0a5d8fae55@baylibre.com>
Date:   Mon, 21 Aug 2023 16:24:18 +0200
From:   Julien Panis <jpanis@...libre.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
        vigneshr@...com, Julien Panis <jpanis@...libre.com>
Subject: [PATCH] bus: ti-sysc: Use fsleep() instead of usleep_range() in
 sysc_reset()

The am335x-evm started producing boot errors because of subtle timing
changes:

Unhandled fault: external abort on non-linefetch (0x1008) at 0xf03c1010
...
sysc_reset from sysc_probe+0xf60/0x1514
sysc_probe from platform_probe+0x5c/0xbc
...

The fix consists in using the appropriate sleep function in sysc reset.
For flexible sleeping, fsleep is recommended. Here, sysc delay parameter
can take any value in [0 - 255] us range. As a result, fsleep() should
be used, calling udelay() for a sysc delay lower than 10 us.

Signed-off-by: Julien Panis <jpanis@...libre.com>
Fixes: e709ed70d122 ("bus: ti-sysc: Fix missing reset delay handling")
---
Fix boot errors for am335x-evm in sysc_reset(), by using fsleep() instead
of usleep_range() function. Thus, udelay() will be called if the configured
sysc delay is lower than 10 us (which is usually the case, since the value
set in the device tree is currently 2 us).
---
 drivers/bus/ti-sysc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/bus/ti-sysc.c b/drivers/bus/ti-sysc.c
index 4cb23b9e06ea..59b8bdd9203e 100644
--- a/drivers/bus/ti-sysc.c
+++ b/drivers/bus/ti-sysc.c
@@ -2147,8 +2147,7 @@ static int sysc_reset(struct sysc *ddata)
 	}
 
 	if (ddata->cfg.srst_udelay)
-		usleep_range(ddata->cfg.srst_udelay,
-			     ddata->cfg.srst_udelay * 2);
+		fsleep(ddata->cfg.srst_udelay);
 
 	if (ddata->post_reset_quirk)
 		ddata->post_reset_quirk(ddata);

---
base-commit: f7757129e3dea336c407551c98f50057c22bb266
change-id: 20230821-fix-ti-sysc-reset-5c164051345b

Best regards,
-- 
Julien Panis <jpanis@...libre.com>