From: "Sean O. Stalley" <sean.stalley@intel.com>
To: bhelgaas@google.com, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: "Sean O. Stalley" <sean.stalley@intel.com>
Subject: [PATCH] Read ID & Pointer from PCI Capabilities List in 1 call
Date: Thu, 2 Apr 2015 14:10:19 -0700 [thread overview]
Message-ID: <1428009019-19563-1-git-send-email-sean.stalley@intel.com> (raw)
Reading both fields at the same time lets us parse the
list with half the number of configspace reads.
Signed-off-by: Sean O. Stalley <sean.stalley@intel.com>
---
drivers/pci/pci.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5e3c8e9..db7f3d6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -145,19 +145,22 @@ static int __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn,
u8 pos, int cap, int *ttl)
{
u8 id;
+ u16 ent;
+
+ pci_bus_read_config_byte(bus, devfn, pos, &pos);
while ((*ttl)--) {
- pci_bus_read_config_byte(bus, devfn, pos, &pos);
if (pos < 0x40)
break;
pos &= ~3;
- pci_bus_read_config_byte(bus, devfn, pos + PCI_CAP_LIST_ID,
- &id);
+ pci_bus_read_config_word(bus, devfn, pos, &ent);
+
+ id = ent & 0xff;
if (id == 0xff)
break;
if (id == cap)
return pos;
- pos += PCI_CAP_LIST_NEXT;
+ pos = (ent >> 8);
}
return 0;
}
--
1.9.1
next reply other threads:[~2015-04-02 21:11 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-02 21:10 Sean O. Stalley [this message]
2015-04-09 22:12 ` [PATCH] Read ID & Pointer from PCI Capabilities List in 1 call Bjorn Helgaas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1428009019-19563-1-git-send-email-sean.stalley@intel.com \
--to=sean.stalley@intel.com \
--cc=bhelgaas@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).