Subject: Re: [PATCH v2 0/4] Patches to allow consistent mmc / mmcblk numbering
 w/ device tree
To: Doug Anderson <dianders@chromium.org>,
        Russell King - ARM Linux <linux@arm.linux.org.uk>
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Cc: Ulf Hansson <ulf.hansson@linaro.org>,
        Jaehoon Chung <jh80.chung@samsung.com>,
        Shawn Lin <shawn.lin@rock-chips.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Stefan Agner <stefan@agner.ch>,
        "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
        Brian Norris <computersforpeace@gmail.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Heiko Stuebner <heiko@sntech.de>, Jisheng Zhang <jszhang@marvell.com>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        devicetree-spec@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Venu Byravarasu <vbyravarasu@nvidia.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Jon Hunter <jonathanh@nvidia.com>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Pawel Moll <pawel.moll@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Grant Grundler <grundler@chromium.org>,
        Kumar Gala <galak@codeaurora.org>,
        "Luca Porzio (lporzio)" <lporzio@micron.com>,
        Rob Herring <robh+dt@kernel.org>,
        Chaotian Jing <chaotian.jing@mediatek.com>,
        Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
        Sudeep Holla <sudeep.holla@arm.com>, zhonghui.fu@linux.intel.com,
        kirill.shutemov@linux.intel.com
From: Peter Hurley <peter@hurleysoftware.com>
Message-ID: <5723F514.4@hurleysoftware.com>
Date: Fri, 29 Apr 2016 16:58:12 -0700
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On 04/29/2016 04:01 PM, Doug Anderson wrote:
> * serial allows numbering devices by alias.

Which is in fact a total nightmare.

While stable device order is mandatory in serial because of
console command line parameters and existing userspace expectations,
it is the number one barrier to providing a shared ttyS namespace
for mixed uart platforms.

Stable device order has a very real (and often unforeseen) maintenance
burden.

For example, I noticed these patches are strictly for DT.
I'm assuming that's because guaranteeing stable device order for
mmc in general is more difficult; eg., by performing minimal scan
serially and more expensive portion of the probe async.

Regards,
Peter Hurley