[PATCH v3 4/4] ARM: OMAP: gpmc: add DT bindings for GPMC timings and NAND

[Philip, Avinash]

On Mon, Nov 05, 2012 at 18:28:22, Daniel Mack wrote:
> On 05.11.2012 12:03, Philip, Avinash wrote:
> > On Fri, Nov 02, 2012 at 20:55:56, Daniel Mack wrote:
> >> This patch adds basic DT bindings for OMAP GPMC.
> >>
> >> The actual peripherals are instanciated from child nodes within the GPMC
> >> node, and the only type of device that is currently supported is NAND.
> >>
> >> Code was added to parse the generic GPMC timing parameters and some
> >> documentation with examples on how to use them.
> >>
> >> Successfully tested on an AM33xx board.
> >>
> >> Signed-off-by: Daniel Mack <zonque at gmail.com>
> > [...]
> >> +
> >> +		nand at 0,0 {
> >> +			reg = <0 0 0>; /* CS0, offset 0 */
> >> +			nand-bus-width = <16>;
> >> +			nand-ecc-mode = "none";
> >> +
> >> +			gpmc,sync-clk = <0>;
> >> +			gpmc,cs-on = <0>;
> >> +			gpmc,cs-rd-off = <36>;
> >> +			gpmc,cs-wr-off = <36>;
> >> +			gpmc,adv-on = <6>;
> >> +			gpmc,adv-rd-off = <24>;
> >> +			gpmc,adv-wr-off = <36>;
> >> +			gpmc,we-off = <30>;
> >> +			gpmc,oe-off = <48>;
> >> +			gpmc,access = <54>;
> >> +			gpmc,rd-cycle = <72>;
> >> +			gpmc,wr-cycle = <72>;
> >> +			gpmc,wr-access = <30>;
> >> +			gpmc,wr-data-mux-bus = <0>;
> >> +
> >> +			#address-cells = <1>;
> >> +			#size-cells = <1>;
> >> +
> > 
> > Can you take the timings (for example) from arago tree. The timings is tested in am335x-evm
> > So the timings can be directly used to populate GPMC timings. Timings can found at
> > 
> > http://arago-project.org/git/projects/?p=linux-am33x.git;a=commitdiff;
> > h=66bfbd2c5b35dc81edce0c24843c476161ab5978;hp=370630359cb8db711cf0941cd2a242e28ccfb61e
> > 
> > [...]
> >> +static int gpmc_probe_dt(struct platform_device *pdev)
> > 
> > Can you take care of the following section mismatch.
> > WARNING: vmlinux.o(.text+0x1e2d0): Section mismatch in reference
> > from the function gpmc_probe_dt() to the function .init.text:gpmc_nand_init().
> 
> Sore, both fixed for v4.
> 
> > [...]
> >> +
> >> +		val = of_get_nand_ecc_mode(child);
> >> +		if (val >= 0)
> >> +			gpmc_nand_data->ecc_opt = val;
> > 
> > This will fail for BCH. Index of "soft_bch" is 5 & also don't have selection
> > option between for BCH4 & BCH8 also.
> > Can you use the of_property_read_u32 (as done early) to pass the ecc selection
> > from dt file. This will help selection of BCH4 & BCH8 ecc options.
> 
> Hmm. Shouldn't we rather teach of_get_nand_ecc_mode() that two modes and
> bring the enum in sync?

ecc_opt is for selecting different ecc layout and not for selecting ecc mode.

In omap2 driver NAND_ECC_HW ecc mode supports 3 ecc layout
	OMAP_ECC_HAMMING_CODE_HW_ROMCODE
	OMAP_ECC_BCH4_CODE_HW
	OMAP_ECC_BCH8_CODE_HW

So selection of ecc layout data should come from DT not ecc mode.

Thanks
Avinash

> 
> 
> Daniel
> 
> 
>