This is a note to let you know that I've just added the patch titled serial: stm32: move dma_request_chan() before clk_prepare_enable() to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: serial-stm32-move-dma_request_chan-before-clk_prepar.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 91f169be5f40713e5884bef17e6059a7a2b1216e Author: Valentin Caron <valentin.caron@xxxxxxxxxxx> Date: Fri Nov 18 18:06:02 2022 +0100 serial: stm32: move dma_request_chan() before clk_prepare_enable() [ Upstream commit 0d114e9ff940ebad8e88267013bf96c605a6b336 ] If dma_request_chan() returns a PROBE_DEFER error, clk_disable_unprepare() will be called and USART clock will be disabled. But early console can be still active on the same USART. While moving dma_request_chan() before clk_prepare_enable(), the clock won't be taken in case of a DMA PROBE_DEFER error, and so it doesn't need to be disabled. Then USART is still clocked for early console. Fixes: a7770a4bfcf4 ("serial: stm32: defer probe for dma devices") Reported-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> Signed-off-by: Valentin Caron <valentin.caron@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20221118170602.1057863-1-valentin.caron@xxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index ce7ff7a0207f..5c60960e185d 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -1363,22 +1363,10 @@ static int stm32_usart_serial_probe(struct platform_device *pdev) if (!stm32port->info) return -EINVAL; - ret = stm32_usart_init_port(stm32port, pdev); - if (ret) - return ret; - - if (stm32port->wakeup_src) { - device_set_wakeup_capable(&pdev->dev, true); - ret = dev_pm_set_wake_irq(&pdev->dev, stm32port->port.irq); - if (ret) - goto err_deinit_port; - } - stm32port->rx_ch = dma_request_chan(&pdev->dev, "rx"); - if (PTR_ERR(stm32port->rx_ch) == -EPROBE_DEFER) { - ret = -EPROBE_DEFER; - goto err_wakeirq; - } + if (PTR_ERR(stm32port->rx_ch) == -EPROBE_DEFER) + return -EPROBE_DEFER; + /* Fall back in interrupt mode for any non-deferral error */ if (IS_ERR(stm32port->rx_ch)) stm32port->rx_ch = NULL; @@ -1392,6 +1380,17 @@ static int stm32_usart_serial_probe(struct platform_device *pdev) if (IS_ERR(stm32port->tx_ch)) stm32port->tx_ch = NULL; + ret = stm32_usart_init_port(stm32port, pdev); + if (ret) + goto err_dma_tx; + + if (stm32port->wakeup_src) { + device_set_wakeup_capable(&pdev->dev, true); + ret = dev_pm_set_wake_irq(&pdev->dev, stm32port->port.irq); + if (ret) + goto err_deinit_port; + } + if (stm32port->rx_ch && stm32_usart_of_dma_rx_probe(stm32port, pdev)) { /* Fall back in interrupt mode */ dma_release_channel(stm32port->rx_ch); @@ -1428,19 +1427,11 @@ static int stm32_usart_serial_probe(struct platform_device *pdev) pm_runtime_set_suspended(&pdev->dev); pm_runtime_put_noidle(&pdev->dev); - if (stm32port->tx_ch) { + if (stm32port->tx_ch) stm32_usart_of_dma_tx_remove(stm32port, pdev); - dma_release_channel(stm32port->tx_ch); - } - if (stm32port->rx_ch) stm32_usart_of_dma_rx_remove(stm32port, pdev); -err_dma_rx: - if (stm32port->rx_ch) - dma_release_channel(stm32port->rx_ch); - -err_wakeirq: if (stm32port->wakeup_src) dev_pm_clear_wake_irq(&pdev->dev); @@ -1450,6 +1441,14 @@ static int stm32_usart_serial_probe(struct platform_device *pdev) stm32_usart_deinit_port(stm32port); +err_dma_tx: + if (stm32port->tx_ch) + dma_release_channel(stm32port->tx_ch); + +err_dma_rx: + if (stm32port->rx_ch) + dma_release_channel(stm32port->rx_ch); + return ret; }