linux-kernel - Re: [PATCH 1/3] tty: serial: fsl_lpuart: move dev_info

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Message-ID: <e9ee810ff8f9df34451de3b1d2b7c04f@walle.cc>
Date:   Wed, 25 Mar 2020 10:15:08 +0100
From:   Michael Walle <michael@...le.cc>
To:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Jiri Slaby <jslaby@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Leonard Crestez <leonard.crestez@....com>
Subject: Re: [PATCH 1/3] tty: serial: fsl_lpuart: move dev_info_once()

Am 2020-03-24 19:47, schrieb Michael Walle:
> Don't take the spinlock and use dev_info_once(). This may cause a hang
> because the console takes this spinlock, too. Just print this info 
> after
> we've released the lock.
> 
> Fixes: 159381df1442f ("tty: serial: fsl_lpuart: fix DMA operation when
> using IOMMU")
> Reported-by: Leonard Crestez <leonard.crestez@....com>
> Signed-off-by: Michael Walle <michael@...le.cc>

Because the patch subject was renamed: This patch series is superseded
by the v2:
  
https://lore.kernel.org/linux-serial/20200325090658.25967-1-michael@walle.cc/

I didn't include the 3/3 RFC patch though. This is a bigger change, 
which
should be carefully reviewed by the maintainer of the fsl_lpuart.c.

-michael


> ---
>  drivers/tty/serial/fsl_lpuart.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c 
> b/drivers/tty/serial/fsl_lpuart.c
> index 9c6a018b1390..960fc2658f19 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1517,9 +1517,6 @@ static void lpuart_tx_dma_startup(struct
> lpuart_port *sport)
> 
>  	sport->dma_tx_chan = dma_request_chan(sport->port.dev, "tx");
>  	if (IS_ERR(sport->dma_tx_chan)) {
> -		dev_info_once(sport->port.dev,
> -			      "DMA tx channel request failed, operating without tx DMA 
> (%ld)\n",
> -			      PTR_ERR(sport->dma_tx_chan));
>  		sport->dma_tx_chan = NULL;
>  		goto err;
>  	}
> @@ -1551,9 +1548,6 @@ static void lpuart_rx_dma_startup(struct
> lpuart_port *sport)
> 
>  	sport->dma_rx_chan = dma_request_chan(sport->port.dev, "rx");
>  	if (IS_ERR(sport->dma_rx_chan)) {
> -		dev_info_once(sport->port.dev,
> -			      "DMA rx channel request failed, operating without rx DMA 
> (%ld)\n",
> -			      PTR_ERR(sport->dma_rx_chan));
>  		sport->dma_rx_chan = NULL;
>  		goto err;
>  	}
> @@ -1601,6 +1595,13 @@ static int lpuart_startup(struct uart_port 
> *port)
> 
>  	spin_unlock_irqrestore(&sport->port.lock, flags);
> 
> +	if (!sport->dma_rx_chan)
> +		dev_info_once(sport->port.dev,
> +			      "DMA rx channel request failed, operating without rx DMA\n");
> +	if (!sport->dma_tx_chan)
> +		dev_info_once(sport->port.dev,
> +			      "DMA tx channel request failed, operating without tx DMA\n");
> +
>  	return 0;
>  }
> 
> @@ -1653,13 +1654,20 @@ static int lpuart32_startup(struct uart_port 
> *port)
> 
>  	lpuart32_setup_watermark_enable(sport);
> 
> -
>  	lpuart_rx_dma_startup(sport);
>  	lpuart_tx_dma_startup(sport);
> 
>  	lpuart32_configure(sport);
> 
>  	spin_unlock_irqrestore(&sport->port.lock, flags);
> +
> +	if (!sport->dma_rx_chan)
> +		dev_info_once(sport->port.dev,
> +			      "DMA rx channel request failed, operating without rx DMA\n");
> +	if (!sport->dma_tx_chan)
> +		dev_info_once(sport->port.dev,
> +			      "DMA tx channel request failed, operating without tx DMA\n");
> +
>  	return 0;
>  }