linux-kernel - Re: [PATCH] serial: 8250_lpss: Unconditionally set PCI master for Quark

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Message-ID: <CAHp75VdVagWk1P2X7Tp3mgGGeJoU_dbxyTiyZ-Hz=VxjF2VX3g@mail.gmail.com>
Date:   Thu, 5 Jan 2017 23:54:41 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jan Kiszka <jan.kiszka@...mens.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] serial: 8250_lpss: Unconditionally set PCI master for Quark

On Wed, Jan 4, 2017 at 10:48 PM, Jan Kiszka <jan.kiszka@...mens.com> wrote:
> MSI needs it as well.
>
> Should have no practical impact, though, as DMA is always available on
> the Quark. But given the few users of pci_alloc_irq_vectors so far, this
> incorrect pattern may spread otherwise.
>

One question below.

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Fixes: 3f3a46951e02 ("serial: 8250_lpss: set PCI master only for private DMA")
> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
> ---
>  drivers/tty/serial/8250/8250_lpss.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
> index f09f68a..9315197 100644
> --- a/drivers/tty/serial/8250/8250_lpss.c
> +++ b/drivers/tty/serial/8250/8250_lpss.c
> @@ -183,7 +183,6 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
>         if (ret)
>                 return;
>
> -       pci_set_master(pdev);
>         pci_try_set_mwi(pdev);

Does it make sense to move MWI there as well?

>
>         /* Special DMA address for UART */
> @@ -216,6 +215,8 @@ static int qrk_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
>         struct pci_dev *pdev = to_pci_dev(port->dev);
>         int ret;
>
> +       pci_set_master(pdev);
> +
>         ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
>         if (ret < 0)
>                 return ret;
> --
> 2.1.4



-- 
With Best Regards,
Andy Shevchenko