From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH v7 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller To: Miquel Raynal CC: Boris Brezillon , Jianxin Pan , , Yixun Lan , David Woodhouse , Brian Norris , Marek Vasut , Richard Weinberger , Jerome Brunet , Neil Armstrong , Martin Blumenstingl , Carlo Caione , Kevin Hilman , Rob Herring , Jian Hu , Hanjie Lin , Victor Wan , , , References: <1542386439-30166-1-git-send-email-jianxin.pan@amlogic.com> <1542386439-30166-3-git-send-email-jianxin.pan@amlogic.com> <20181207102456.1dc67e07@xps13> <823825a3-86fb-9a20-ae29-85cc52d44093@amlogic.com> <20181210123809.5ade45c4@bbrezillon> <79a797c2-f37f-7f7c-e907-2d3c2283ec2d@amlogic.com> <20181210155057.38788656@xps13> <20181211085445.68e57e0e@xps13> From: Liang Yang Message-ID: <356aed95-518d-7cd0-4337-184f181472ad@amlogic.com> Date: Tue, 11 Dec 2018 16:36:47 +0800 MIME-Version: 1.0 In-Reply-To: <20181211085445.68e57e0e@xps13> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Miquel, Thanks for your quickly reply. On 2018/12/11 15:54, Miquel Raynal wrote: > Hi Liang, > > Liang Yang wrote on Tue, 11 Dec 2018 09:56:25 > +0800: > >> Hi Miquel, >> >> On 2018/12/10 22:50, Miquel Raynal wrote: >>> Hi Liang, >>> >>> Liang Yang wrote on Mon, 10 Dec 2018 20:12:39 >>> +0800: >>> >>>> On 2018/12/10 19:38, Boris Brezillon wrote: >>>>> On Mon, 10 Dec 2018 19:23:46 +0800 >>>>> Liang Yang wrote: >>>>> >>>>>> + mtd->ecc_stats.failed++; >>>>>>>> + continue; >>>>>>>> + } >>>>>>>> + mtd->ecc_stats.corrected += ECC_ERR_CNT(*info); >>>>>>>> + bitflips = max_t(u32, bitflips, ECC_ERR_CNT(*info)); >>>>>>>> + } >>>>>>> >>>>>>> Are you sure you handle correctly empty pages with bf? >>>>>>> >> if scramble is enable, i would say yes here. >>>>>> when scramble is disabled, i am considering how to use the helper >>>>>> nand_check_erased_ecc_chunk, but it seems that i can't get the ecc >>>>>> bytes which is caculated by ecc engine.by the way, nfc dma doesn't send >>>>>> out the ecc parity bytes. >>>>> >>>>> Even if the ECC engine is disabled? >>>>> >> No. >>>> When ECC engine is disabled, it can read the ecc parity bytes ; but there is another problem that i need to consider how code struct looks better when reading error with ecc opened and then try to raw read. >>>> Is there a good idea? >>> >>> When reading with ECC enabled, in case of uncorrectable error you >>> must re-read without ECC, then check if the page is empty or not with >>> the core helpers (nand_check_erased_*()). >>> >>> Is this what you meant? >>> >> yes. when uncorrectable ECC error, i need firstly read out the ECC bytes without ECC engine and then use the helper nand_check_erased_ecc_chunk to check if blank page. >> Of course, the precondition is without scrambler, or the bland page can be detected by meson NFC. > > A suppose you meant "blank page"? If yes, then you don't need the > helper to check for only-0xFF pages. If the controller tells you if the > page was blank, then just check for that bit. > i think not. we need to return back the previous problem that how i can get the bitflips of one blank page. i think i need the helper. > > Thanks, > Miquèl > > . >