> On Thu, Aug 22, 2013 at 07:56:57AM +0000, Gupta, Pekon wrote: > If anything, the device entry should somehow describe the various ecc > options > that the hardware implements (if you can't derive that from the compatible > value, which I think you can?). > > > Also I'll try to explain how below ecc-scheme selection is linked to TI > Hardware. > > TI SoC uses two separate H/W engines for calculating and correcting ECC. > > (a) GPMC: General Purpose Memory Controller which calculates ECC also. > > (b) ELM: Error Locator Module which just locates errors in BCHx code only. > > > > *Reason-1*: All OMAP platforms have (a) GPMC h/w engine, but some > > legacy OMAP platforms do not have (b) ELM h/w engine. Such older > > platforms use S/W lib/bch.c libraries for ECC error detection. > > Ok, so then you just need a binary "elm-engine" property to indicate > that the hardware does have the engine. > > > Therefore in-order to keep the driver consistent for all platforms we > > needed to keep so many ECC options alive. Like below you would see > > two versions of BCH8 and BCH4 > > - bch8_code_hw (supported on new devices with ELM h/w engine) > > - bch8_code_hw_detection_sw (kept for legacy devices) > > All you need to specify is what ECC format is used. I.e. BCH8. Whether the > hardware or software will be used to calculate the checksums and > detect/correct > errors is a driver decision, and not something that the device tree needs to > specify. > > > *Reason-2*: Also H/W ECC schemes have different ECC layout, which is > > compatible to ROM code. Thus end-to-end NAND boot would work > > only with xx_code_hw schemes only. > > So you should describe what the layout in use is. Wouldn't it be > possible to make the software handle the same layout as the hardware > engine if needed? I.e. the decision of using HW or SW is not a property > of the hardware and shouldn't be described in the device tree. > Sorry I was caught up in some other priority work, therefore could not update this. But I have recently posted another version with your feedbacks incorporated. Please review them, whenever possible. http://lists.infradead.org/pipermail/linux-mtd/2013-September/048611.html Patch series at: http://lists.infradead.org/pipermail/linux-mtd/2013-September/048613.html Thank you With regards, pekon ��.n��������+%������w��{.n�����{�������ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
