From: Hante Meuleman <firstname.lastname@example.org>
To: Ian Molton <email@example.com>, firstname.lastname@example.org
Cc: Arend Van Spriel <email@example.com>,
Franky Lin <firstname.lastname@example.org>
Subject: RE: brcmfmac bus level addressing issues.
Date: Tue, 18 Jul 2017 12:35:05 +0200 [thread overview]
Message-ID: <email@example.com> (raw)
I've really no idea what you mean. Brcmf_pcie_select_core is redundant?
Care to try to boot a device without this function? Called all over the
place? Hell no, it is default pointing to PCIE2 and functions which need
to map the window to another core will do so, temporarily, but move it
back to PCIE2, at least that is the idea, may be you found a bug? We are
for sure not going to hide the selecting of the window in the read/write
routines, that would result in a giant amount of overhead. Currently PCIE
devices reach 1.5Gpbs, we need to go faster than that in the near future.
We don't want just change that to make it bit nicer..... Why do you need
to see the same in the SDIO and PCIE drivers? SDIO and PCIE differ in many
aspects. Sure some things can be improved in or the other, but they sure
don't need to look alike.
It may be ugly, but thusfar it has not caused bugs (and there won't be
large changes in the near future where it will cause bugs). The concept in
pcie bus part is simple. The main core to select is PCIE2 (once you have
booted and established initial communication with firmware) and every
routine which needs to access another core will change the window
temporarily and set it back once done. Please don't mess with this, it
works, it is clear and it is fast.
From: Ian Molton [mailto:firstname.lastname@example.org]
Sent: Tuesday, July 18, 2017 11:45 AM
Cc: Arend Van Spriel; Franky Lin; Hante Meuleman
Subject: RFC: brcmfmac bus level addressing issues.
Its come to my attention that there is a substantial disparity between the
PCIe and SDIO variants of the driver when it comes to handlign writes via
The SDIO bus code checks, upon every (32 bit) access, wether the backplane
window is in the right place, and only updates it if it has actually
The PCIe code sets the window *regardless* of wether its changed, on
*every single* write.
The SDIO code has no explicit selection of the window address based on the
The PCIe code uses brcmf_pcie_select_core(), which, ultimately, appears to
be totally redundant, due to the above mentioned 32 bit access code
setting the window register regardless of its current value.
Can we standardise how this is supposed to work? Its ugly, and its going
to cause bugs, ultimately. I suspect its probably the cause of the code I
mentioned in my recent patch titled "brcmfmac: HACK - stabilise the value
of ->sbwad in use for some xfer routines."
We really *dont* want to call brcmf_pcie_select_core() all over the place.
Its inefficient, traversing a list as it does, when all it does is return
a pointer that never actually changes, to the core structures that contain
I'd propose we do what I've done in my SDIO patch set - we call
brcmf_chip_get_core() *once* after the chip has been probed, and store the
The window register setting can be hidden in the read32/write32 buscore
ops, and will never be incorrect from that point, and the code can simply
use a flat address space model. A single if() has got to be less costly
than writing the register on overy single read32/write32...
Anyhow, whatever we decide to do, can we do the same thing in both bus
next prev parent reply other threads:[~2017-07-18 10:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-18 9:45 RFC: brcmfmac bus level addressing issues Ian Molton
2017-07-18 10:35 ` Hante Meuleman [this message]
2017-07-18 11:27 ` Ian Molton
[not found] ` <email@example.com>
[not found] ` <firstname.lastname@example.org>
2017-07-18 15:14 ` Ian Molton
2017-07-18 20:44 ` Arend van Spriel
2017-07-18 22:45 ` Ian Molton
2017-07-19 8:39 ` Hante Meuleman
2017-07-19 9:33 ` Ian Molton
2017-07-19 11:47 ` Arend van Spriel
2017-07-19 19:25 ` Ian Molton
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:
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
* 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).