linux-kernel - Re: [PATCH] gpu:drm:Change calls to mdelay to msleep in the functions,send_pkg_prepare and send_pkg_done for the file,mdfld_dsi_pkg

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Date:	Mon, 12 Jan 2015 16:14:49 +0000
From:	Alan Cox <alan@...ux.intel.com>
To:	Thierry Reding <treding@...dia.com>
Cc:	Nicholas Krause <xerofoify@...il.com>, airlied@...ux.ie,
	airlied@...hat.com, damien.lespiau@...el.com,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpu:drm:Change calls to mdelay to msleep in the
 functions,send_pkg_prepare and send_pkg_done for the
 file,mdfld_dsi_pkg_sender.c

On Mon, 2015-01-12 at 17:12 +0100, Thierry Reding wrote:
> On Mon, Jan 12, 2015 at 01:29:27PM +0000, Alan Cox wrote:
> > On Sat, 2015-01-10 at 23:31 -0500, Nicholas Krause wrote:
> > > Changes various calls in the functions,send_pkg_prepare and send_pkg_done
> > > for mdelay to msleep. These changes are needed due to use working with
> > > various sleep modes supported by this hardware and thus needing to sleep
> > > for a small duration instead of using the respectful delay function due
> > > to the need to sleep rather then busy loop the CPU(s) and waste CPU cycles
> > > on the system that could be used to handle other tasks.
> > > 
> > > Signed-off-by: Nicholas Krause <xerofoify@...il.com>
> > 
> > NAK
> > 
> > Like every other TODO you've been mucking with at random this one is
> > there for a reason.
> > 
> > We can't sleep at this point.
> 
> From a quick look it seems like the only reason why we can't sleep is
> because sender->lock is a spinlock. But it would seem that it could
> simply be a mutex, in which case the delays could become sleeps.
> 
> Do you happen to remember if there were specific reasons to make this a
> spinlock rather than a mutex?

I don't remember the full details and since I don't currently have a
test platform for it, and its obsolete I don't want to touch it.

If someone else does fine, but they need to verify it on real hardware.

Alan


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