From: Kenny Levinsen <kl@kl.wtf>
To: Jiri Kosina <jikos@kernel.org>,
Dmitry Torokhov <dtor@chromium.org>,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
Douglas Anderson <dianders@chromium.org>,
Hans de Goede <hdegoede@redhat.com>,
Maxime Ripard <mripard@kernel.org>,
Kai-Heng Feng <kai.heng.feng@canonical.com>,
Johan Hovold <johan+linaro@kernel.org>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
Radoslaw Biernacki <rad@chromium.org>,
Lukasz Majczak <lma@chromium.org>
Cc: Kenny Levinsen <kl@kl.wtf>
Subject: [PATCH v3 2/3] HID: i2c-hid: Retry HID descriptor read to wake up STM devices
Date: Sat, 27 Apr 2024 00:47:08 +0200 [thread overview]
Message-ID: <20240426225739.2166-3-kl@kl.wtf> (raw)
In-Reply-To: <20240426225739.2166-1-kl@kl.wtf>
Some STM microcontrollers need 400µs after rising clock edge in order to
come out of their deep sleep state. This in turn means that the first
command sent to them will fail on a bus error.
Retry once on bus error to see if the device came alive, otherwise treat
the error as if no device was present like before.
Link: https://lore.kernel.org/all/20240405102436.3479210-1-lma@chromium.org/#t
Co-developed-by: Radoslaw Biernacki <rad@chromium.org>
Co-developed-by: Lukasz Majczak <lma@chromium.org>
Tested-by: Lukasz Majczak <lma@chromium.org>
Reviewed-by: Lukasz Majczak <lma@chromium.org>
Signed-off-by: Kenny Levinsen <kl@kl.wtf>
---
drivers/hid/i2c-hid/i2c-hid-core.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 6ffa43d245b4..6ac1b11fb675 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -991,8 +991,17 @@ static int __i2c_hid_core_probe(struct i2c_hid *ihid)
struct hid_device *hid = ihid->hid;
int ret;
+ /*
+ * Some STM-based devices need 400µs after a rising clock edge to wake
+ * from deep sleep, which in turn means that our first command will
+ * fail on a bus error. Retry the command in this case.
+ */
ret = i2c_hid_fetch_hid_descriptor(ihid);
- if (ret < 0) {
+ if (ret == -ENXIO) {
+ usleep_range(400, 500);
+ ret = i2c_hid_fetch_hid_descriptor(ihid);
+ }
+ if (ret) {
i2c_hid_dbg(ihid, "failed to fetch HID descriptor: %d\n", ret);
return ret;
}
--
2.44.0
next prev parent reply other threads:[~2024-04-26 22:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 22:47 [PATCH v3 0/3] HID: i2c-hid: Probe and wake device with HID descriptor fetch Kenny Levinsen
2024-04-26 22:47 ` [PATCH v3 1/3] HID: i2c-hid: Rely on HID descriptor fetch to probe Kenny Levinsen
2024-04-27 3:21 ` Dmitry Torokhov
2024-04-27 13:20 ` Kenny Levinsen
2024-04-30 21:41 ` Dmitry Torokhov
2024-05-01 5:24 ` Kenny Levinsen
2024-05-01 19:09 ` Dmitry Torokhov
2024-05-01 23:09 ` Kenny Levinsen
2024-04-26 22:47 ` Kenny Levinsen [this message]
2024-04-26 22:47 ` [PATCH v3 3/3] HID: i2c-hid: Align i2c_hid_set_power() retry with HID descriptor read Kenny Levinsen
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