[PATCH 6.0 0686/1073] serial: stm32: move dma_request_chan() before clk_prepare_enable()

Greg Kroah-Hartman
2022-12-28T16:20:58Z

From: Valentin Caron <valentin.caron@foss.st.com>

[ 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@pengutronix.de>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20221118170602.1057863-1-valentin.caron@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/stm32-usart.c | 47 ++++++++++++++++----------------
1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 9a875558f5ef..1f8aad186908 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -1681,22 +1681,10 @@ 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;
@@ -1710,6 +1698,17 @@ 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);
@@ -1746,19 +1745,11 @@ 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);

@@ -1768,6 +1759,14 @@ 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;
}

--
2.35.1