linux-kernel - Re: [PATCH] mcb: mcb-pci: Only remap the 1st 0x200 bytes of BAR 0

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Message-ID: <CAErSpo4WCrwS-KyiESd_LUh-1n5TumMvW5drV7FxCp7AFYX8TQ@mail.gmail.com>
Date:	Tue, 28 Oct 2014 10:22:33 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Johannes Thumshirn <johannes.thumshirn@....de>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andreas Werner <andreas.werner@....de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mcb: mcb-pci: Only remap the 1st 0x200 bytes of BAR 0

On Tue, Oct 28, 2014 at 10:11 AM, Johannes Thumshirn
<johannes.thumshirn@....de> wrote:
> Currently it is not possible to have a kernel with built-in MCB attached
> devices. This results out of the fact that mcb-pci requests PCI BAR 0, then
> parses the chameleon table and calls the driver's probe function before
> releasing BAR 0 again. When building the kernel with modules this is not a
> problem (and therefore it wasn't detected by my tests yet).
>
> A solution is to only remap the 1st 0x200 bytes of a Chameleon PCI device.
> 0x200 bytes is the maximum size of a Chameleon v2 Table.
>
> Also this patch stops disabling the PCI device on successful registration of MCB
> devices.
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@....de>
> Suggested-by: Bjorn Helgaas <bhelgaas@...gle.com>

Looks good to me!

Reviewed-by: Bjorn Helgaas <bhelgaas@...gle.com>

> ---
>  drivers/mcb/mcb-internal.h |  1 +
>  drivers/mcb/mcb-pci.c      | 27 ++++++++++++++++++---------
>  2 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mcb/mcb-internal.h b/drivers/mcb/mcb-internal.h
> index f956ef2..fb7493d 100644
> --- a/drivers/mcb/mcb-internal.h
> +++ b/drivers/mcb/mcb-internal.h
> @@ -7,6 +7,7 @@
>  #define PCI_DEVICE_ID_MEN_CHAMELEON    0x4d45
>  #define CHAMELEON_FILENAME_LEN         12
>  #define CHAMELEONV2_MAGIC              0xabce
> +#define CHAM_HEADER_SIZE               0x200
>
>  enum chameleon_descriptor_type {
>         CHAMELEON_DTYPE_GENERAL = 0x0,
> diff --git a/drivers/mcb/mcb-pci.c b/drivers/mcb/mcb-pci.c
> index b591819..5e1bd5d 100644
> --- a/drivers/mcb/mcb-pci.c
> +++ b/drivers/mcb/mcb-pci.c
> @@ -17,6 +17,7 @@
>
>  struct priv {
>         struct mcb_bus *bus;
> +       phys_addr_t mapbase;
>         void __iomem *base;
>  };
>
> @@ -31,8 +32,8 @@ static int mcb_pci_get_irq(struct mcb_device *mdev)
>
>  static int mcb_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  {
> +       struct resource *res;
>         struct priv *priv;
> -       phys_addr_t mapbase;
>         int ret;
>         int num_cells;
>         unsigned long flags;
> @@ -47,19 +48,21 @@ static int mcb_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>                 return -ENODEV;
>         }
>
> -       mapbase = pci_resource_start(pdev, 0);
> -       if (!mapbase) {
> +       priv->mapbase = pci_resource_start(pdev, 0);
> +       if (!priv->mapbase) {
>                 dev_err(&pdev->dev, "No PCI resource\n");
>                 goto err_start;
>         }
>
> -       ret = pci_request_region(pdev, 0, KBUILD_MODNAME);
> -       if (ret) {
> -               dev_err(&pdev->dev, "Failed to request PCI BARs\n");
> +       res = request_mem_region(priv->mapbase, CHAM_HEADER_SIZE,
> +                                KBUILD_MODNAME);
> +       if (IS_ERR(res)) {
> +               dev_err(&pdev->dev, "Failed to request PCI memory\n");
> +               ret = PTR_ERR(res);
>                 goto err_start;
>         }
>
> -       priv->base = pci_iomap(pdev, 0, 0);
> +       priv->base = ioremap(priv->mapbase, CHAM_HEADER_SIZE);
>         if (!priv->base) {
>                 dev_err(&pdev->dev, "Cannot ioremap\n");
>                 ret = -ENOMEM;
> @@ -84,7 +87,7 @@ static int mcb_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>
>         priv->bus->get_irq = mcb_pci_get_irq;
>
> -       ret = chameleon_parse_cells(priv->bus, mapbase, priv->base);
> +       ret = chameleon_parse_cells(priv->bus, priv->mapbase, priv->base);
>         if (ret < 0)
>                 goto err_drvdata;
>         num_cells = ret;
> @@ -93,8 +96,10 @@ static int mcb_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>
>         mcb_bus_add_devices(priv->bus);
>
> +       return 0;
> +
>  err_drvdata:
> -       pci_iounmap(pdev, priv->base);
> +       iounmap(priv->base);
>  err_ioremap:
>         pci_release_region(pdev, 0);
>  err_start:
> @@ -107,6 +112,10 @@ static void mcb_pci_remove(struct pci_dev *pdev)
>         struct priv *priv = pci_get_drvdata(pdev);
>
>         mcb_release_bus(priv->bus);
> +
> +       iounmap(priv->base);
> +       release_region(priv->mapbase, CHAM_HEADER_SIZE);
> +       pci_disable_device(pdev);
>  }
>
>  static const struct pci_device_id mcb_pci_tbl[] = {
> --
> 1.9.1
--
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