Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1768476Ab2KOQwc (ORCPT ); Thu, 15 Nov 2012 11:52:32 -0500 Received: from mail-wi0-f172.google.com ([209.85.212.172]:47198 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1768411Ab2KOQwb (ORCPT ); Thu, 15 Nov 2012 11:52:31 -0500 From: Grant Likely Subject: Re: [PATCH v5 4/4] misc: sram: add support for configurable allocation order To: Philipp Zabel Cc: linux-kernel@vger.kernel.org, Arnd Bergmann , Greg Kroah-Hartman , Rob Herring , Paul Gortmaker , Shawn Guo , Richard Zhao , Huang Shijie , Dong Aisheng , Matt Porter , kernel@pengutronix.de, devicetree-discuss@lists.ozlabs.org In-Reply-To: <1352985095.2399.184.camel@pizza.hi.pengutronix.de> References: <1350570453-24546-1-git-send-email-p.zabel@pengutronix.de> <1350570453-24546-5-git-send-email-p.zabel@pengutronix.de> <20121114191551.5E8673E0B7C@localhost> <1352985095.2399.184.camel@pizza.hi.pengutronix.de> Date: Thu, 15 Nov 2012 16:52:26 +0000 Message-Id: <20121115165226.EFE553E194B@localhost> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2985 Lines: 66 On Thu, 15 Nov 2012 14:11:35 +0100, Philipp Zabel wrote: > Am Mittwoch, den 14.11.2012, 19:15 +0000 schrieb Grant Likely: > > On Thu, 18 Oct 2012 16:27:33 +0200, Philipp Zabel wrote: > > > From: Matt Porter > > > > > > Adds support for setting the genalloc pool's minimum allocation > > > order via DT or platform data. The allocation order is optional > > > for both the DT property and platform data case. If it is not > > > present then the order defaults to PAGE_SHIFT to preserve the > > > current behavior. > > > > > > Signed-off-by: Matt Porter > > > Signed-off-by: Philipp Zabel > > > --- > > > Documentation/devicetree/bindings/misc/sram.txt | 12 ++++++++++- > > > drivers/misc/sram.c | 14 ++++++++++++- > > > include/linux/platform_data/sram.h | 25 +++++++++++++++++++++++ > > > 3 files changed, 49 insertions(+), 2 deletions(-) > > > create mode 100644 include/linux/platform_data/sram.h > > > > > > diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt > > > index b64136c..b1705ec 100644 > > > --- a/Documentation/devicetree/bindings/misc/sram.txt > > > +++ b/Documentation/devicetree/bindings/misc/sram.txt > > > @@ -8,10 +8,20 @@ Required properties: > > > > > > - reg : SRAM iomem address range > > > > > > -Example: > > > +Optional properties: > > > + > > > +- alloc-order : Minimum allocation order for the SRAM pool > > > > Looks okay, but I think the property name is confusing. I for one had > > no idea what 'order' would be and why it was important. I had to read > > the code to figure it out. > > > > It does raise the question though of what is this binding actually > > for? Does it reflect a limitation of the SRAM? or of the hardware using > > the SRAM? Or is it an optimization? How do you expect to use it? > > If I am not mistaken, it is about the expected use case. A driver > allocating many small buffers would quickly fill small SRAMs if the > allocations were of PAGE_SIZE granularity. > > I wonder if a common allocation size (say, 512 bytes instead of > PAGE_SIZE) can be found that every prospective user could be reasonably > happy with? > > > Assuming it is appropriate to put into the device tree, I'd suggest a > > different name. Instead of 'order', how about 'sram-alloc-align' (in > > address bits) or 'sram-alloc-min-size' (in bytes). > > A size in bytes would be the most obvious to me, although that allows to > enter values that are not a power of two. That may be just fine. If the driver can only do powers of 2, then it will just have to round up. g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/