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From: Michael Zaidman <michael.zaidman@gmail.com>
To: chrysh@christina-quast.de, daniel.beer@igorinstitute.com,
	jikos@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
	linux-serial@vger.kernel.org, ilpo.jarvinen@linux.intel.com,
	johan@kernel.org, gregkh@linuxfoundation.org, equinox@diac24.net,
	michael.zaidman@gmail.com
Subject: [PATCH v1 06/19] hid-ft260: uart: enable wakeup workaround
Date: Sat, 10 Feb 2024 23:51:34 +0200	[thread overview]
Message-ID: <20240210215147.77629-7-michael.zaidman@gmail.com> (raw)
In-Reply-To: <20240210215147.77629-1-michael.zaidman@gmail.com>

The FT260 has a "power saving mode" that causes the device to switch
to a 30 kHz oscillator if there's no activity for 5 seconds.
Unfortunately, this mode can only be disabled by reprogramming
internal fuses, or external eeprom if exists.

One effect of this mode is to cause data loss on an Rx line at baud
rates higher than 4800 after being idle for longer than 5 seconds.

We work around this by sending a dummy report at least once per 4.8
seconds if the UART is in use. But it is not acctivated in the
"[PATCH v4 RESEND] hid-ft260: Add serial driver"
https://lore.kernel.org/all/20231218093153.192268-1-contact@christina-quast.de/

It causes data loss on the Rx line at the driver's default 9600 baud rate.

Enable periodic dummy report to prevent data loss on Rx line upon exiting
from power saving mode.

Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
---
 drivers/hid/hid-ft260.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 3d6beac0b8b6..19599e64c6be 100644
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c
@@ -1575,7 +1575,7 @@ static int ft260_uart_probe(struct hid_device *hdev, struct ft260_device *dev)
 	INIT_WORK(&dev->wakeup_work, ft260_uart_do_wakeup);
 	// FIXME: Do I need that if I have cancel_work_sync?
 	// FIXME: are all kfifo access secured by lock? with irq or not?
-	dev->reschedule_work = false;
+	dev->reschedule_work = true;
 	/* Work not started at this point */
 	timer_setup(&dev->wakeup_timer, ft260_uart_start_wakeup, 0);
 
-- 
2.40.1


  parent reply	other threads:[~2024-02-10 21:53 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-10 21:51 [PATCH v1 00/19] hid-ft260: Fixes for serial driver patch v4 Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 01/19] hid-ft260: fix incompatible-pointer-types error Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 02/19] hid-ft260: fix Wformat warning Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 03/19] hid-ft260: fix i2c driver regression in ft260_raw_event Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 04/19] hid-ft260: remove dead code in ft260_uart_receive_chars Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 05/19] hid-ft260: fix unprotected write_buf concurrent access Michael Zaidman
2024-02-10 21:51 ` Michael Zaidman [this message]
2024-02-10 21:51 ` [PATCH v1 07/19] hid-ft260: depend wakeup workaround activation on uart baud rate Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 08/19] hid-ft260: depend wakeup workaround activation on eeprom config Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 09/19] hid-ft260: uart: wakeup device early to not lose rx data Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 10/19] hid-ft260: uart: do not configure baud rate twice Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 11/19] hid-ft260: uart: do not disable wakeup workaround twice Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 12/19] hid-ft260: uart: use kfifo_avail for fifo write room check Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 13/19] hid-ft260: improve usb interface type detection logic Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 14/19] hid-ft260: uart: cleanup and refactoring Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 15/19] hid-ft260: uart: remove FIXME for wake-up workaround Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 16/19] hid-ft260: uart: suppress unhandled report 0xb1 dmesg Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 17/19] hid-ft260: uart: arm wake-up timer unconditionally on tty session start Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 18/19] hid-ft260: uart: fix rx data loss after device reopening Michael Zaidman
2024-02-10 21:51 ` [PATCH v1 19/19] hid-ft260: uart: improve write performance Michael Zaidman
2024-02-23 21:22   ` Michael Zaidman
2024-02-13 10:20 ` [PATCH v1 00/19] hid-ft260: Fixes for serial driver patch v4 Jiri Kosina
2024-02-23 13:07   ` Christina Quast

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