From: Tony Lindgren <tony@atomide.com>
To: Roger Quadros <rogerq@ti.com>
Cc: Mark Brown <broonie@kernel.org>, "Gupta, Pekon" <pekon@ti.com>,
"dwmw2@infradead.org" <dwmw2@infradead.org>,
"computersforpeace@gmail.com" <computersforpeace@gmail.com>,
"kyungmin.park@samsung.com" <kyungmin.park@samsung.com>,
"ezequiel.garcia@free-electrons.com"
<ezequiel.garcia@free-electrons.com>,
"javier@dowhile0.org" <javier@dowhile0.org>,
"Nori, Sekhar" <nsekhar@ti.com>,
"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
ivan.khoronzhuk@ti.com, Alexander Shiyan <shc_work@mail.ru>
Subject: Re: [PATCH 05/36] mtd: nand: omap: Move IRQ handling from GPMC to NAND driver
Date: Tue, 1 Jul 2014 06:16:19 -0700 [thread overview]
Message-ID: <20140701131618.GQ28884@atomide.com> (raw)
In-Reply-To: <53B2893E.5020306@ti.com>
* Roger Quadros <rogerq@ti.com> [140701 03:13]:
> On 06/13/2014 03:08 PM, Tony Lindgren wrote:
> > * Roger Quadros <rogerq@ti.com> [140613 04:43]:
> >>
> >> OK. I agree about using some kind of abstraction instead of direct access.
> >
> > Yes and like we chatted on irc, adding a syscon mapping for for
> > the NAND specific registers might do the trick here.
>
> After looking at the syscon driver, which relies on regmap, it seems that regmap was designed for slow control busses like I2C/SPI and using it for NAND controller register access will have a significant negative impact on performance. In the NAND case the register writes are used for each NAND command cycle and the reads for ECC checks (every page).
>
> See how much code regmap_read and regmap_mmio_read() translates to for a simple register read i.e. readl().
> http://lxr.free-electrons.com/source/drivers/base/regmap/regmap.c#L1944
> http://lxr.free-electrons.com/source/drivers/base/regmap/regmap-mmio.c#L129
>
> So I'm not so sure of using regmap/syscon for NAND controller register access.
OK yes I agree, it's not a good solution for a constant
register access that's needed for the ECC registers.
> Could there be any other abstraction method of sharing the register space between GPMC and NAND driver?
> I've also added Ivan to the thread, the author of memory/ti-aemif.c driver, to check if he faced any issues with shared register access of the AEMIF/NAND registers.
If there's no common framework available for GPMC to implement,
it's best to just export few functions from gpmc.c for the ECC
calculations.
Regards,
Tony
next prev parent reply other threads:[~2014-07-01 13:16 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-11 8:56 [PATCH 00/36] OMAP: GPMC: Restructure and move OMAP GPMC driver out of mach-omap2 Roger Quadros
2014-06-11 8:56 ` [PATCH 01/36] ARM: OMAP3: hwmod: Fix gpmc memory resource space Roger Quadros
2014-06-13 7:13 ` Tony Lindgren
2014-06-13 7:15 ` Roger Quadros
2014-06-11 8:56 ` [PATCH 02/36] ARM: dts: OMAP2+: Fix GPMC register space size Roger Quadros
2014-06-11 8:56 ` [PATCH 03/36] ARM: OMAP2+: gpmc: Add platform data Roger Quadros
2014-06-11 8:56 ` [PATCH 04/36] ARM: OMAP2+: gpmc: Add gpmc timings and settings to " Roger Quadros
2014-06-11 8:56 ` [PATCH 05/36] mtd: nand: omap: Move IRQ handling from GPMC to NAND driver Roger Quadros
2014-06-13 7:18 ` Tony Lindgren
2014-06-13 7:38 ` Roger Quadros
2014-06-13 7:58 ` Tony Lindgren
2014-06-13 8:13 ` Gupta, Pekon
2014-06-13 8:23 ` Roger Quadros
2014-06-13 10:46 ` Tony Lindgren
2014-06-13 11:42 ` Roger Quadros
2014-06-13 12:08 ` Tony Lindgren
2014-07-01 10:11 ` Roger Quadros
2014-07-01 13:16 ` Tony Lindgren [this message]
2014-06-11 8:56 ` [PATCH 06/36] mtd: nand: omap: Move gpmc_update_nand_reg to nand driver Roger Quadros
2014-06-13 7:19 ` Tony Lindgren
2014-06-11 8:56 ` [PATCH 07/36] mtd: nand: omap: Move NAND write protect code from GPMC to NAND driver Roger Quadros
2014-06-13 7:20 ` Tony Lindgren
2014-06-11 8:56 ` [PATCH 08/36] mtd: nand: omap: Copy platform data parameters to omap_nand_info data Roger Quadros
2014-06-11 8:56 ` [PATCH 09/36] mtd: nand: omap: Clean up device tree support Roger Quadros
2014-06-11 8:56 ` [PATCH 10/36] ARM: dts: OMAP2+: Fix NAND device nodes Roger Quadros
2014-06-13 7:21 ` Tony Lindgren
2014-06-11 8:56 ` [PATCH 11/36] mtd: nand: omap: Update DT binding documentation Roger Quadros
2014-06-11 8:56 ` [PATCH 12/36] ARM: dts: omap3-beagle: Add NAND device Roger Quadros
2014-06-11 8:56 ` [PATCH 13/36] ARM: OMAP2+: gpmc.c: sanity check bank-width DT property Roger Quadros
2014-06-11 8:56 ` [PATCH 14/36] ARM: OMAP2+: gpmc: Allow drivers to reconfigure GPMC settings & timings Roger Quadros
2014-06-13 7:25 ` Tony Lindgren
2014-06-13 7:44 ` Roger Quadros
2014-06-13 8:04 ` Tony Lindgren
2014-06-11 8:56 ` [PATCH 15/36] ARM: OMAP2+: gpmc: Allow drivers to query GPMC_CLK period Roger Quadros
2014-06-13 7:26 ` Tony Lindgren
2014-06-13 7:48 ` Roger Quadros
2014-06-11 8:56 ` [PATCH 16/36] mtd: onenand: omap: Remove regulator management code Roger Quadros
2014-06-11 8:56 ` [PATCH 17/36] ARM: OMAP2+: gpmc-onenand: Use Async settings/timings by default Roger Quadros
2014-06-11 8:56 ` [PATCH 18/36] ARM: OMAP2+: gpmc-onenand: Move Synchronous setting code to drivers/ Roger Quadros
2014-06-13 7:55 ` Tony Lindgren
2014-06-13 8:30 ` Roger Quadros
2014-06-11 8:56 ` [PATCH 19/36] mtd: onenand: omap: Use devres managed resources Roger Quadros
2014-06-11 8:56 ` [PATCH 20/36] mtd: onenand: omap: Clean up device tree support Roger Quadros
2014-06-11 8:56 ` [PATCH 21/36] ARM: dts: OMAP2+: Fix OneNAND device nodes Roger Quadros
2014-06-11 8:56 ` [PATCH 22/36] ARM: OMAP2+: gmpc: add gpmc_generic_init() Roger Quadros
2014-06-11 8:56 ` [PATCH 23/36] ARM: OMAP2+: gpmc: use platform data to configure CS space and poplulate device Roger Quadros
2014-06-11 8:56 ` [PATCH 24/36] ARM: OMAP2+: gpmc: add NAND specific setup Roger Quadros
2014-06-11 8:56 ` [PATCH 25/36] ARM: OMAP2+: gpmc: Support multiple Chip Selects per device Roger Quadros
2014-06-11 8:56 ` [PATCH 26/36] ARM: OMAP2+: gpmc-smc91x: Get rid of retime() from omap_smc91x_platform_data Roger Quadros
2014-06-11 8:56 ` [PATCH 27/36] ARM: OMAP2+: usb-tusb6010: Use omap_gpmc_retime() Roger Quadros
2014-06-11 8:56 ` [PATCH 28/36] ARM: OMAP2+: nand: Update gpmc_nand_init() to use generic_gpmc_init() Roger Quadros
2014-06-11 8:56 ` [PATCH 29/36] ARM: OMAP2+: gpmc-smc91x: Use gpmc_generic_init() Roger Quadros
2014-06-11 8:56 ` [PATCH 30/36] ARM: OMAP2+: gpmc-smsc911x: " Roger Quadros
2014-06-11 8:56 ` [PATCH 31/36] ARM: OMAP2: usb-tusb6010: " Roger Quadros
2014-06-11 8:56 ` [PATCH 32/36] ARM: OMAP2+: onenand: " Roger Quadros
2014-06-11 8:56 ` [PATCH 33/36] ARM: OMAP2+: board-flash: Use gpmc_generic_init() for NOR Roger Quadros
2014-06-11 8:56 ` [PATCH 34/36] ARM: OMAP2+: gpmc: Make externally unused functions/defines private Roger Quadros
2014-06-11 8:56 ` [PATCH 35/36] ARM: OMAP2+: gpmc: move GPMC driver into drivers/memory Roger Quadros
2014-06-11 11:45 ` [resend][PATCH " Roger Quadros
2014-06-11 8:56 ` [PATCH 36/36] ARM: OMAP2+: defconfig: Enable TI GPMC driver Roger Quadros
2014-06-11 11:52 ` [PATCH 00/36] OMAP: GPMC: Restructure and move OMAP GPMC driver out of mach-omap2 Javier Martinez Canillas
2014-06-11 11:54 ` Roger Quadros
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