From: Mason <slash.tmp@free.fr>
To: Marc Zyngier <marc.zyngier@arm.com>,
Bjorn Helgaas <helgaas@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: Robin Murphy <robin.murphy@arm.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Liviu Dudau <liviu.dudau@arm.com>,
David Laight <david.laight@aculab.com>,
linux-pci <linux-pci@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Thibaud Cornic <thibaud_cornic@sigmadesigns.com>,
Phuong Nguyen <phuong_nguyen@sigmadesigns.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v0.2] PCI: Add support for tango PCIe host bridge
Date: Fri, 24 Mar 2017 00:40:16 +0100 [thread overview]
Message-ID: <9fffedd4-6292-b662-a588-a68fe7380af6@free.fr> (raw)
In-Reply-To: <310db9dd-7db6-2106-2e53-f0083b2d3758@free.fr>
On 23/03/2017 18:03, Mason wrote:
> The host bridge actually supports 256 MSIs.
>
> IIUC, what you suggested on IRC is that I support 256 in the driver,
> and only read the status for *enabled* MSIs.
>
> Pseudo-code:
>
> for every 32-bit blob in the enabled bitmap
> if the value is non-zero
> lookup the corresponding status reg
>
> Problem is that a BITMAP is unsigned long (as you point out below).
> So I'm not sure how to iterate 32-bits at a time over the BITMAP.
Something along these lines:
DECLARE_BITMAP(enabled, 256);
unsigned int pos = 0;
while ((pos = find_next_bit(enabled, 256, pos)) < 256) {
int offset = (pos / 32) * 4;
u32 status = readl_relaxed(status + offset);
/* Handle each pos set in status */
pos = round_up(pos, 32);
}
You mentioned a bug in my code (due to the platform endianness)
when passing the result of readl_relaxed to the bitops routine...
How is one supposed to iterate over status?
I'm not yet seeing this endianness issue, since (status & BIT(i))
provides the status of MSI_i, irrespective of endianness.
Although I see that arch/arm/include/asm/bitops.h declares
BE and LE variants... I'm confused.
Regards.
next prev parent reply other threads:[~2017-03-23 23:40 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 13:05 [RFC PATCH v0.2] PCI: Add support for tango PCIe host bridge Mason
2017-03-23 14:22 ` Marc Zyngier
2017-03-23 17:03 ` Mason
2017-03-23 23:40 ` Mason [this message]
2017-03-24 18:22 ` Marc Zyngier
2017-03-27 14:35 ` Mason
2017-03-27 14:46 ` Thomas Gleixner
2017-03-27 15:18 ` Mason
2017-03-24 18:47 ` Marc Zyngier
2017-03-27 15:53 ` Mason
2017-03-27 17:09 ` Marc Zyngier
2017-03-27 19:44 ` Mason
2017-03-27 21:07 ` Marc Zyngier
2017-03-27 22:04 ` Mason
2017-03-28 8:21 ` Marc Zyngier
2017-04-11 15:13 ` Mason
2017-04-11 15:49 ` Marc Zyngier
2017-04-11 16:26 ` Mason
2017-04-11 16:43 ` Marc Zyngier
2017-04-11 17:52 ` Mason
2017-04-12 8:08 ` Marc Zyngier
2017-04-12 9:50 ` Mason
2017-04-12 9:59 ` Marc Zyngier
2017-04-19 11:19 ` Mason
2017-04-20 8:20 ` Mason
2017-04-20 9:43 ` Marc Zyngier
2017-03-29 11:39 ` Mason
2017-03-30 11:09 ` Mason
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=9fffedd4-6292-b662-a588-a68fe7380af6@free.fr \
--to=slash.tmp@free.fr \
--cc=david.laight@aculab.com \
--cc=helgaas@kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=liviu.dudau@arm.com \
--cc=lorenzo.pieralisi@arm.com \
--cc=marc.zyngier@arm.com \
--cc=phuong_nguyen@sigmadesigns.com \
--cc=robin.murphy@arm.com \
--cc=tglx@linutronix.de \
--cc=thibaud_cornic@sigmadesigns.com \
/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).