Messages in this thread | | | Date | Wed, 11 Nov 2015 11:51:13 -0600 | From | Han Xu <> | Subject | Re: [PATCH] mtd: spi-nor: fsl-quadspi: add big-endian support |
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On Fri, Oct 30, 2015 at 04:49:41AM -0500, Yuan Yao-B46683 wrote: > Hi Fabio Estevam, > > Thanks for your suggestion. > We have an internal discussions for that. > > We think that: > According to the initial commit message of regmap, it is targeting non-memory mapped buses. (regmap: Add generic non-memory mapped register access API) But in the imx2_wdt driver, it is used for memory-mapped register space. So it seems that using such a complex framework just to deal with endian is an over-kill. > > when it is not necessary to enable the clock every time we access the register. > We don't think it is obvious to us how to use it for handling endianness, especially not the way imx2_wdt uses regmap. __regmap_init_mmio_clk() calls regmap_mmio_gen_context() which errors out if reg_format_endian is not REGMAP_ENDIAN_DEFAULT or REGMAP_ENDIAN_NATIVE, and elsewhere regmap-mmio.c It seems only little-endian accessors. > > Although it is possible to add the endianness support in the regmap_mmio driver, we don't see too much value in using it especially > > So we think: > static void qspi_writel(struct fsl_qspi *q, u32 val, void __iomem > *addr) { > if (q->big_endian) > iowrite32be(val, addr); > else > iowrite32(val, addr); > } > This way is an easier, more effective solution to do the endian issue. > > How about your think?
I think the implement is fine, but I prefer to use quirk rather than read from dts? Please also rebase the patch to latest l2-mtd code.
> > Best Regards, > Yuan Yao > > On Sat, Oct 24, 2015 at 11:47 PM, Fabio Estevam <festevam@gmail.com> wrote: > > On Fri, Oct 23, 2015 at 5:53 AM, Yuan Yao <yao.yuan@freescale.com> wrote: > > > > > +static void qspi_writel(struct fsl_qspi *q, u32 val, void __iomem > > > +*addr) { > > > + if (q->big_endian) > > > + iowrite32be(val, addr); > > > + else > > > + iowrite32(val, addr); > > > +} > > > > I suggest you to implement regmap support for this driver instead. > > > > Take a look at drivers/watchdog/imx2_wdt.c for a reference. > > > > Then you only need to pass 'big-endian' as a property for the qspi in the .dtsi > > file and regmap core will take care of endianness.
-- Best Regards,
Han "Allen" Xu
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