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From: Matt Porter <mporter-l0cyMroinI0@public.gmane.org>
To: Paul Mundt <lethal-M7jkjyW5wf5g9hUCZPvPmw@public.gmane.org>
Cc: Fabio Estevam
	<fabio.estevam-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
	Dong Aisheng
	<dong.aisheng-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org,
	Greg Kroah-Hartman
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>,
	Paul Gortmaker
	<paul.gortmaker-CWA4WttNNZF54TAoqtyWWQ@public.gmane.org>,
	Richard Zhao
	<richard.zhao-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
	Javier Martin
	<javier.martin-N4RbWZIug12MkV8/HQOAswC/G2K4zDHf@public.gmane.org>,
	Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>,
	Huang Shijie <shijie8-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCH v8 2/4] misc: Generic on-chip SRAM allocation driver
Date: Mon, 4 Feb 2013 12:02:04 -0500	[thread overview]
Message-ID: <20130204170204.GX2244@beef> (raw)
In-Reply-To: <20130204155344.GA14171-M7jkjyW5wf5g9hUCZPvPmw@public.gmane.org>

On Tue, Feb 05, 2013 at 12:53:45AM +0900, Paul Mundt wrote:
> On Mon, Feb 04, 2013 at 12:32:16PM +0100, Philipp Zabel wrote:
> > This driver requests and remaps a memory region as configured in the
> > device tree. It serves memory from this region via the genalloc API.
> > It optionally enables the SRAM clock.
> > 
> > Other drivers can retrieve the genalloc pool from a phandle pointing
> > to this drivers' device node in the device tree.
> > 
> > The allocation granularity is hard-coded to 32 bytes for now,
> > to make the SRAM driver useful for the 6502 remoteproc driver.
> > There is overhead for bigger SRAMs, where only a much coarser
> > allocation granularity is needed: At 32 bytes minimum allocation
> > size, a 256 KiB SRAM needs a 1 KiB bitmap to track allocations.
> > 
> > Signed-off-by: Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> > Reviewed-by: Shawn Guo <shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> 
> How exactly is this "generic" if you have randomly hard-coded an
> allocation granularity that is larger than half of the in-tree SRAM pool
> users today can even support? Did you even bother to look at in-tree SRAM
> pool users other than the one you are working on?
>
> There also doesn't seem to be any real reason for the hard-coding either,
> this information could easily be fetched via platform data or the device
> tree, and the driver in question would simply need to be able to
> determine whether the size is suitable for it or not.

Please see http://thread.gmane.org/gmane.linux.kernel/1377702 for the
original discussion on my patch for configurable allocation granularity.
I believe there was an implied agreement from Grant that it was ok if we
went with a more descriptive name even though it hits the grey area of
not describing hardware.

-Matt

WARNING: multiple messages have this Message-ID (diff)
From: Matt Porter <mporter@ti.com>
To: Paul Mundt <lethal@linux-sh.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>,
	linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Grant Likely <grant.likely@secretlab.ca>,
	Rob Herring <rob.herring@calxeda.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Shawn Guo <shawn.guo@linaro.org>,
	Richard Zhao <richard.zhao@freescale.com>,
	Huang Shijie <shijie8@gmail.com>,
	Dong Aisheng <dong.aisheng@linaro.org>,
	Fabio Estevam <fabio.estevam@freescale.com>,
	Javier Martin <javier.martin@vista-silicon.com>,
	kernel@pengutronix.de, devicetree-discuss@lists.ozlabs.org
Subject: Re: [PATCH v8 2/4] misc: Generic on-chip SRAM allocation driver
Date: Mon, 4 Feb 2013 12:02:04 -0500	[thread overview]
Message-ID: <20130204170204.GX2244@beef> (raw)
In-Reply-To: <20130204155344.GA14171@linux-sh.org>

On Tue, Feb 05, 2013 at 12:53:45AM +0900, Paul Mundt wrote:
> On Mon, Feb 04, 2013 at 12:32:16PM +0100, Philipp Zabel wrote:
> > This driver requests and remaps a memory region as configured in the
> > device tree. It serves memory from this region via the genalloc API.
> > It optionally enables the SRAM clock.
> > 
> > Other drivers can retrieve the genalloc pool from a phandle pointing
> > to this drivers' device node in the device tree.
> > 
> > The allocation granularity is hard-coded to 32 bytes for now,
> > to make the SRAM driver useful for the 6502 remoteproc driver.
> > There is overhead for bigger SRAMs, where only a much coarser
> > allocation granularity is needed: At 32 bytes minimum allocation
> > size, a 256 KiB SRAM needs a 1 KiB bitmap to track allocations.
> > 
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> > Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
> 
> How exactly is this "generic" if you have randomly hard-coded an
> allocation granularity that is larger than half of the in-tree SRAM pool
> users today can even support? Did you even bother to look at in-tree SRAM
> pool users other than the one you are working on?
>
> There also doesn't seem to be any real reason for the hard-coding either,
> this information could easily be fetched via platform data or the device
> tree, and the driver in question would simply need to be able to
> determine whether the size is suitable for it or not.

Please see http://thread.gmane.org/gmane.linux.kernel/1377702 for the
original discussion on my patch for configurable allocation granularity.
I believe there was an implied agreement from Grant that it was ok if we
went with a more descriptive name even though it hits the grey area of
not describing hardware.

-Matt

  parent reply	other threads:[~2013-02-04 17:02 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-04 11:32 [PATCH v8 0/4] Add generic driver for on-chip SRAM Philipp Zabel
2013-02-04 11:32 ` [PATCH v8 1/4] genalloc: add devres support, allow to find a managed pool by device Philipp Zabel
2013-02-04 11:32 ` [PATCH v8 2/4] misc: Generic on-chip SRAM allocation driver Philipp Zabel
2013-02-04 15:53   ` Paul Mundt
     [not found]     ` <20130204155344.GA14171-M7jkjyW5wf5g9hUCZPvPmw@public.gmane.org>
2013-02-04 17:02       ` Matt Porter [this message]
2013-02-04 17:02         ` Matt Porter
2013-02-05  8:57     ` Philipp Zabel
2013-02-08 20:16   ` Grant Likely
2013-02-08 20:16     ` Grant Likely
2013-02-11 18:15     ` Philipp Zabel
2013-02-12 18:09       ` Grant Likely
2013-02-04 11:32 ` [PATCH v8 3/4] media: coda: use genalloc API Philipp Zabel
2013-02-05  8:12   ` javier Martin
2013-02-04 11:32 ` [PATCH v8 4/4] ARM: dts: add sram for imx53 and imx6q Philipp Zabel

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