From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: Lucas Kannebley Tavares <lucaskt@linux•vnet.ibm.com>
Cc: David Airlie <airlied@linux•ie>,
linux-pci@vger•kernel.org, dri-devel@lists•freedesktop.org,
Brian King <brking@linux•vnet.ibm.com>,
Thadeu Cascardo <cascardo@linux•vnet.ibm.com>,
Bjorn Helgaas <bhelgaas@google•com>,
Alex Deucher <alexander.deucher@amd•com>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCHv2 3/3] ppc64: implemented pcibios_get_speed_cap_mask
Date: Wed, 20 Mar 2013 06:39:47 +0100 [thread overview]
Message-ID: <1363757987.18880.31.camel@pasglop> (raw)
In-Reply-To: <1363757079-23550-4-git-send-email-lucaskt@linux.vnet.ibm.com>
On Wed, 2013-03-20 at 02:24 -0300, Lucas Kannebley Tavares wrote:
> Implementation of a architecture-specific pcibios_get_speed_cap_mask.
> This implementation detects bus capabilities based on OF
> ibm,pcie-link-speed-stats property.
The problem with your approach is that it's not a runtime detection...
If the pseries machine is compiled into the kernel binary, it will
override pcibios_get_speed_cap_mask() using the device-tree, regardless
of whether the machine is currently booted on a pseries machine or not.
This wouldn't be a big problem if the pseries
pcibios_get_speed_cap_mask() was capable of doing a fallback to the
generic one if the device-tree property is absent but that isn't the
case.
I think what you need to do is:
- Make it so the generic one can be called by the override. This can
look a bit tricky but it's better that way. One way to do it is to have
the actual implementation be in a __pci_* variant called by the weak
pcibios_* variant
- Move the powerpc on to arch/powerpc/kernel/pci-common.c and make
it call a ppc_md.pcibios_get_speed_cap_mask(). If the hook is absent
(NULL), make it call the generic one
- pseries can then populate the hook in ppc_md. with its custom
variant.
Cheers,
Ben.
next prev parent reply other threads:[~2013-03-20 5:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-20 5:24 [PATCHv2 0/3] PCI Speed Cap Fixes for ppc64 Lucas Kannebley Tavares
2013-03-20 5:24 ` [PATCHv2 1/3] pci: added pcie_get_speed_cap_mask function Lucas Kannebley Tavares
2013-03-26 18:39 ` Bjorn Helgaas
2013-03-27 15:25 ` Benjamin Herrenschmidt
2013-03-27 16:58 ` Bjorn Helgaas
2013-03-20 5:24 ` [PATCHv2 2/3] drm: removed drm_pcie_get_speed_cap_mask function Lucas Kannebley Tavares
2013-03-20 5:24 ` [PATCHv2 3/3] ppc64: implemented pcibios_get_speed_cap_mask Lucas Kannebley Tavares
2013-03-20 5:39 ` Benjamin Herrenschmidt [this message]
2013-03-20 15:34 ` [PATCHv2 0/3] PCI Speed Cap Fixes for ppc64 Jerome Glisse
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