From: Johannes Berg <johannes@sipsolutions.net>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Wey-Yi Guy <wey-yi.w.guy@intel.com>,
Intel Linux Wireless <ilw@linux.intel.com>,
linux-wireless@vger.kernel.org
Subject: Re: [RFC 3/4] iwlwifi: cleanup/fix memory barriers
Date: Mon, 06 Feb 2012 17:13:25 +0100 [thread overview]
Message-ID: <4F2FFC25.8000705@sipsolutions.net> (raw)
In-Reply-To: <1328544564-8696-3-git-send-email-sgruszka@redhat.com> (sfid-20120206_170940_538104_F123CA7E)
On 2/6/2012 5:09 PM, Stanislaw Gruszka wrote:
> wmb(), rmb() are not needed when writel(), readl() are used as
> accessors for MMIO. We use them indirectly via iowrite32(),
> ioread32().
>
> What is needed mmiowb(), for synchronizing writes coming from
> different CPUs on PCIe bridge (see in patch comments). This
> fortunately is not needed on x86, where mmiowb() is just
> defined as compiler barrier. As iwlwifi devices are most likely
> not used on anything other than x86, this is not so important
> fix.
Technically, PCIe bridges can reorder writes as well, so we really need
to do a dummy read somewhere -- we were discussing this internally
recently as well.
johannes
next prev parent reply other threads:[~2012-02-06 16:14 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-06 16:09 [RFC 1/4] iwlwifi: dump stack when fail to gain access to the device Stanislaw Gruszka
2012-02-06 16:08 ` wwguy
2012-02-07 8:01 ` Stanislaw Gruszka
2012-02-07 14:21 ` Guy, Wey-Yi
2012-02-08 10:52 ` Stanislaw Gruszka
2012-02-06 16:09 ` [RFC 2/4] iwlwifi: always check if got h/w access before write Stanislaw Gruszka
2012-02-06 16:13 ` wwguy
2012-02-07 8:05 ` Stanislaw Gruszka
2012-02-07 14:20 ` Guy, Wey-Yi
2012-02-06 16:09 ` [RFC 3/4] iwlwifi: cleanup/fix memory barriers Stanislaw Gruszka
2012-02-06 16:13 ` Johannes Berg [this message]
2012-02-07 8:11 ` Stanislaw Gruszka
2012-02-07 8:25 ` Johannes Berg
2012-02-06 16:09 ` [RFC 4/4] iwlwifi: use writeb,writel,readl directly Stanislaw Gruszka
2012-02-06 16:32 ` wwguy
2012-02-07 8:22 ` Stanislaw Gruszka
2012-02-07 14:22 ` Guy, Wey-Yi
2012-02-10 12:01 ` [RFC 1/4] iwlwifi: dump stack when fail to gain access to the device Stanislaw Gruszka
2012-02-23 10:14 ` Stanislaw Gruszka
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