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From: Wei Yang <weiyang.kernel@gmail.com>
To: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: linux-pci@vger.kernel.org, bhelgaas@google.com,
	benh@kernel.crashing.org, linuxram@us.ibm.com,
	Richard Yang <weiyang@linux.vnet.ibm.com>
Subject: Re: [PATCH 4/8] pci: weak function returns alignment
Date: Fri, 17 Aug 2012 11:00:48 +0800	[thread overview]
Message-ID: <CADLM8XOiHMfwnxBvZU_YF8S9QomcXjy5fb6JyxCrNCjr+sbYOw@mail.gmail.com> (raw)
In-Reply-To: <1343180997-9483-5-git-send-email-shangw@linux.vnet.ibm.com>

2012/7/25 Gavin Shan <shangw@linux.vnet.ibm.com>:
> The patch implements the weak function to return the default I/O
> or memory alignment for P2P bridge. Currently, I/O window has 4KiB
> alignment and memory window is 4MiB aligned by default. On the other
> hand, those platforms (e.g. powernv) that have special requirements
> on the alignment could override the function by themselves.
>
> Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
> ---
>  drivers/pci/setup-bus.c |   21 +++++++++++++++++++++
>  include/linux/pci.h     |    2 ++
>  2 files changed, 23 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 8fa2d4b..c0fb9da 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -690,6 +690,27 @@ static resource_size_t calculate_memsize(resource_size_t size,
>         return size;
>  }
>
> +resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus,
> +                                               unsigned long type)
> +{
> +       return 1;
> +}
> +
> +static resource_size_t window_alignment(struct pci_bus *bus,
> +                                       unsigned long type)
> +{
> +       resource_size_t align = 1, arch_align;
> +
> +       if (type & IORESOURCE_MEM)
> +               align = 1024*1024;      /* 1MiB */
> +       else if (type & IORESOURCE_IO)
> +               align = 4*1024;         /* 4KiB */
> +

If this is a constant, could we use define a macro?
So we don't use to calculate the value every time.
Maybe some compile will be smart enough to optimize this,
still think it is better to give a result.

> +       arch_align = pcibios_window_alignment(bus, type);
> +
> +       return max(align, arch_align);
> +}
> +
>  /**
>   * pbus_size_io() - size the io window of a given bus
>   *
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 9acea4b..34ff2bb 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -988,6 +988,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
>  int pci_cfg_space_size(struct pci_dev *dev);
>  unsigned char pci_bus_max_busnr(struct pci_bus *bus);
>  void pci_setup_bridge(struct pci_bus *bus);
> +resource_size_t pcibios_window_alignment(struct pci_bus *bus,
> +                                        unsigned long type);
>
>  #define PCI_VGA_STATE_CHANGE_BRIDGE (1 << 0)
>  #define PCI_VGA_STATE_CHANGE_DECODES (1 << 1)
> --
> 1.7.5.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html



-- 
Richard Yang
Help You, Help Me

  reply	other threads:[~2012-08-17  3:00 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-25  1:49 [PATCH Resend v7 0/8] minimal alignment for p2p bars Gavin Shan
2012-07-25  1:49 ` [PATCH 1/8] pci: change variable name for find_pci_host_bridge Gavin Shan
2012-07-25  1:49 ` [PATCH 2/8] pci: argument pci_bus " Gavin Shan
2012-07-25  1:49 ` [PATCH 3/8] fiddle with conversion of pci and CPU address Gavin Shan
2012-08-17  3:20   ` Wei Yang
2012-07-25  1:49 ` [PATCH 4/8] pci: weak function returns alignment Gavin Shan
2012-08-17  3:00   ` Wei Yang [this message]
2012-07-25  1:49 ` [PATCH 5/8] pci: resource assignment based on p2p alignment Gavin Shan
2012-07-25  1:49 ` [PATCH 6/8] pci: refactor function pbus_size_mem Gavin Shan
2012-07-25  1:49 ` [PATCH 7/8] ppc/pci: override pcibios_window_alignment Gavin Shan
2012-07-25  1:49 ` [PATCH 8/8] ppc/pnv: I/O and memory alignment for p2p bridges Gavin Shan
2012-08-17  2:49   ` Wei Yang
2012-08-20 13:46 [PATCH V8 0/8] Minimal alignment for p2p bars Gavin Shan
2012-08-20 13:46 ` [PATCH 4/8] pci: weak function returns alignment Gavin Shan

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