On 04.07.2023 16:41, Miquel Raynal wrote: > Hi Arseniy, > >>>>>> Yes, this code looks strange. 'nsectors' is used to calculate space in OOB >>>>>> that could be used by ECC engine (this value will be passed as 'oobavail' >>>>>> to 'nand_ecc_choose_conf()'). Idea of 512 is to consider "worst" case >>>>>> for ECC, e.g. minimal number of bytes for ECC engine (and at the same time >>>>>> maximum number of free bytes). For Meson, if ECC step size is 512, then we >>>>>> have 4 x 2 free bytes in OOB (if step size if 1024 then we have 2 x 2 free >>>>>> bytes in OOB). >>>>>> >>>>>> I think this code could be reworked in the following way: >>>>>> >>>>>> if ECC step size is already known here (from DTS), calculate 'nsectors' using >>>>>> given value (div by 512 for example). Otherwise calculate 'nsectors' in the >>>>>> current manner: >>>>> >>>>> It will always be known when these function are run. There is no >>>>> guessing here. >>>> >>>> Hm I checked, that but if step size is not set in DTS, here it will be 0, >>>> then it will be selected in 'nand_ecc_choose_conf()' according provided 'ecc_caps' >>>> and 'oobavail'... >>>> >>>> Anyway, I'll do the following thing: >>>> >>>> int nsectors; >>>> >>>> if (nand->ecc.size) >>>> nsectors = mtd->writesize / nand->ecc.size; <--- this is for 512 ECC >>> >>> You should set nand->ecc.size in ->attach_chip() instead. >> >> Sorry, didn't get it... if ECC step size is set in DTS, then here, in chip attach >> callback it will be already known (DT part was processed in 'rawnand_dt_init()'). >> If ECC step size is unknown (e.g. 0 here), 'nand_ecc_choose_conf()' will set it >> according provided ecc caps. What do You mean for "You should set ..." ? > > The current approach is wrong, it decides the number of ECC chunks > (called nsectors in the driver) and then asks the core to decide the > number of ECC chunks to use. Yes! I was also confused about that. > > Just provide mtd->oobsize - 2 as last parameter and then rely on the > core's logic to find the right ECC step-size/strength? > > There is no point in requesting a particular step size without a > specific strength, or? So I believe you should provide both in the DTS > if you want particular parameters to be applied, otherwise you can let > the core decide what is best. So I think this could be a separated patch as it doesn't rely on 512 step size ECC support for Meson and may be it should be "Fix" tagged. Thanks, Arseniy > > Thanks, > Miquèl
