From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 17CC2261B70 for ; Tue, 30 Dec 2025 15:56:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767110162; cv=none; b=XH61ZlEfZSNTo6JN0UoF8HDL6zLLnmJqzbajfVuL8Z0ryS5jKreT/qBPmlP2wA6reK+A+nWdSjak3Cplx2GFe2vUn+abvHEhk/zxvqyDZlUlzxcplv1lbWMPQvqkvPm+uJW227pxw7nbFqm01RJTugpUDA/Jx0k7RSiRxjZw9EM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767110162; c=relaxed/simple; bh=UkHFRZSAs6a6NEj8Y5Ft9CZKNqClbG8UOUWLgxKUVHs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OZKK3khFH9Vds+1dMRc9m11RE3f1cKh2uvni5v8NQBbknyiXK2+Br8CvomOvUZB+dOAMtPEIJy4Wzjx06yAizIvdLrnp7Zx6kdfhHg3eq2fB2qf3q4Jjr4FFKYn+bNtFSbjqQwewxmByvB5W3gkdxtrm7uZb+hAjHBV5smqOfAI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GUIa6Jam; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GUIa6Jam" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A817CC4CEFB; Tue, 30 Dec 2025 15:55:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767110160; bh=UkHFRZSAs6a6NEj8Y5Ft9CZKNqClbG8UOUWLgxKUVHs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GUIa6JamdBBpQ9zkvBPppxn/ea0oIXgoVIWDL7SCrL2zpHOJP6TAhBv5TIEtac6bU CkZI9sx5SHYVstkOzeB9PBZpx5WGxxp6sLWjCk8FBS1R79OUZuqLS89ZjD5QROwXmh x5iM6ZmoYXsb2o4gMQ0+A8POaaek9JJb3/zzGjix88T0tYWcjf0jyz9N62lvT2hCPr ONdjd9L72n92BvnS0OK0TZ/pzLbCJmJBtDLucOQuKRQfOI+EvB7GZ1eKYkyV+DgvV3 5E6wgbgshnmw/BOcLxiG/gdKnpUBfYGILb1hcYYv7V9iQZlGEQ2P9sN/WK2+8RDJqA g3+hTXIOXbNqQ== From: Sasha Levin To: stable@vger.kernel.org Cc: "j.turek" , stable , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.12.y 3/3] serial: xilinx_uartps: fix rs485 delay_rts_after_send Date: Tue, 30 Dec 2025 10:55:56 -0500 Message-ID: <20251230155556.2289800-3-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251230155556.2289800-1-sashal@kernel.org> References: <2025122923-amaretto-output-f3dc@gregkh> <20251230155556.2289800-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "j.turek" [ Upstream commit 267ee93c417e685d9f8e079e41c70ba6ee4df5a5 ] RTS line control with delay should be triggered when there is no more bytes in kfifo and hardware buffer is empty. Without this patch RTS control is scheduled right after feeding hardware buffer and this is too early. RTS line may change state before hardware buffer is empty. With this patch delayed RTS state change is triggered when function cdns_uart_handle_tx is called from cdns_uart_isr on CDNS_UART_IXR_TXEMPTY exactly when hardware completed transmission Fixes: fccc9d9233f9 ("tty: serial: uartps: Add rs485 support to uartps driver") Cc: stable Link: https://patch.msgid.link/20251221103221.1971125-1-jakub.turek@elsta.tech Signed-off-by: Jakub Turek Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/xilinx_uartps.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 1d4646c40855..239d28489841 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -431,10 +431,17 @@ static void cdns_uart_handle_tx(void *dev_id) struct tty_port *tport = &port->state->port; unsigned int numbytes; unsigned char ch; + ktime_t rts_delay; if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) { /* Disable the TX Empty interrupt */ writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IDR); + /* Set RTS line after delay */ + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { + cdns_uart->tx_timer.function = &cdns_rs485_rx_callback; + rts_delay = ns_to_ktime(cdns_calc_after_tx_delay(cdns_uart)); + hrtimer_start(&cdns_uart->tx_timer, rts_delay, HRTIMER_MODE_REL); + } return; } @@ -451,13 +458,6 @@ static void cdns_uart_handle_tx(void *dev_id) /* Enable the TX Empty interrupt */ writel(CDNS_UART_IXR_TXEMPTY, cdns_uart->port->membase + CDNS_UART_IER); - - if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED && - (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port))) { - hrtimer_update_function(&cdns_uart->tx_timer, cdns_rs485_rx_callback); - hrtimer_start(&cdns_uart->tx_timer, - ns_to_ktime(cdns_calc_after_tx_delay(cdns_uart)), HRTIMER_MODE_REL); - } } /** -- 2.51.0