Hi Frieder, > Hi Lukasz, > > On 21.09.2018 00:13, Lukasz Majewski wrote: > > Hi Frieder, > > > > Please find some more comments regarding the new spi-fsl-qspi.c > > driver. > >> Hi Lukasz, > >> > >> On 20.09.2018 17:00, Lukasz Majewski wrote: > >>> Hi Frieder, > >>> > >>>> Hi Frieder, > >>>> > >>>>> Hi Lukasz, > >>>>> > >>>>> On 19.09.2018 00:42, Lukasz Majewski wrote: > >>>>>> Dear All, > >>>>>> > >>>>>> Maybe I do jump a bit off topic here, but... > >>>>>> > >>>>>> I've read through the following thread: > >>>>>> https://patchwork.ozlabs.org/patch/939885/ > >>>>>> > >>>>>> And it mentions some issues with reading AHB content (buffers) > >>>>>> in fsl-quadspi.c driver discovered when new QuadSPI driver was > >>>>>> developed. > >>>>> > >>>>> The only setup with two chips that is known to be problematic > >>>>> with the new driver, is when both chips are connected to the > >>>>> same bus (e.g. QSPIA) using separate chip selects. > >>>> > >>>> I'm using QSPI0 controller, with two memories connected to > >>>> QSPI0_A and QSPI0_B lines. > >>>> > >>>>> > >>>>> Does your board use this kind of setup, or are the two chips > >>>>> connected two different buses (QSPIA and QSPIB)? > >>>>> > >>>>> Have you tested the new driver? It would be great to receive > >>>>> some more feedback. > >>>> > >>>> I will check (test) this new driver. No problem. > >>> > >>> I've ported your patch on v4.19-rc3. > >>> > >>> I had to fix the "div0 issue" by adding: > >>> if (op->dummy.buswidth && > >>> (op->dummy.nbytes * 8 / op->dummy.buswidth > 64)) > >>> > >>> In fsl_qspi_supports_op() function. > >>> > >>> > >>> Unfortunately, on Vybrid vf610 when testing I do see corruption of > >>> read data from the mtd device: > >>> > >>> ~# hexdump aaa.img > >>> 0000000 464c eec0 baa5 c5ff 7b99 4dfb e0b6 8a2e > >>> 0000010 e98e 5265 683c a635 c069 e402 303f d936 > >>> 0000020 c243 01a7 7064 fce8 e3a9 200a 7e85 28bc > >>> 0000030 4296 a30e 1bb4 88d4 b456 b4a6 f3aa 8cff > >>> 0000040 ffff ffff ffff ffff ffff ffff ffff ffff > >>> * > >>> 0000100 > >>> > >>> ~# hexdump data_test.img > >>> 0000000 464c eec0 baa5 c5ff 7b99 4dfb e0b6 8a2e > >>> 0000010 e98e 5265 683c a635 c069 e402 303f d936 > >>> 0000020 c243 01a7 7064 fce8 e3a9 200a 7e85 28bc > >>> 0000030 4296 a30e 1bb4 88d4 b456 b4a6 f3aa 8cff > >>> 0000040 01c9 462d 0a43 f893 0e42 67f1 57f0 787c > >>> 0000050 49c0 fb2a e514 e954 1d21 affa bac4 38f1 > >>> 0000060 1ca5 ec46 77eb a854 285b 8e21 12d7 f377 > >>> 0000070 b441 2baf ee33 596c 98b6 e71a c1cb 876c > >>> > >>> > >>> Test case: > >>> flash_erase /dev/mtd3 0 1 > >>> dd if=data_test.img of=/dev/mtd3 > >>> dd if=/dev/mtd3 of=aaa.img bs=1 count=256 > >>> > >>> > >>> From the code I see that the AHB buffer has 1024B. It is > >>> accessed in 8 bytes packs. > >>> > >>> This seems like some cache or HW issue.... > >>> > >>> In the old driver, to fix this problem one needed to > >>> 1. Reduce the RX fifo size from 128B to 64B > >>> > >>> 2. Disable (set to 0) the AHB transfer's BUF3CR ADATSZ field - the > >>> transfer size is the same as in LUT. > >>> > >>> (Original patch: https://patchwork.ozlabs.org/patch/675401/) > >> > >> Thanks a lot for doing the test. It seems like Vybrid needs some > >> special handling to work around this problem. > >> So this means the current driver has never worked for Vybrid, as > >> the mentioned patch was never merged!? > >> > >> As these issues seem to be specific to Vybrid and as they seem to > >> exist in the current driver too, I would like to fix them after we > >> have a first version of the new driver that works for the other > >> platforms. > >> > >> I hope we can figure out the other issues soon. > >> > >> Thanks, > >> Frieder > >> > >>> > >>> > >>>> > >>>>> > >>>>>> I do have a setup with qspi0 having two SPI memories connected > >>>>>> (2x16 MiB), and I'm wondering if anybody has some more info > >>>>>> regarding: > >>>>>> > >>>>>> (What's more is that there is a bug in > >>>>>> * the "IP Command Read" in the Vybrid.) found here: > >>> ^^^^^^^^^^^^^^^^^^^^^^^^ - It would be handy to have the > >>> exact explanation of this issue. > >>> > >>>>>> https://elixir.bootlin.com/linux/v4.19-rc4/source/drivers/mtd/spi-nor/fsl-quadspi.c#L671 > > ^^^^^^^^^^^^ - [1] > > > > > > I've looked a bit closer to the new spi-fsl-qspi.c driver and it > > looks like it uses fsl_qspi_exec_op() and then calls > > fsl_qspi_do_op(). > > > > In the last function we setup the QUADSPI_IPCR register to initiate > > the transfer between SPI-NOR and the internal RX buffer. > > > > Please correct me if I'm wrong but it seems to me like we are using > > "IP Command Read" approach here. > > "IP Read" is only used if data size is smaller then RX FIFO size (128 > bytes for Vybrid). I would like to just point out that the "legacy" (in-kernel) driver (fsl_quadspi.c) is using AHB transfers for even small chunks of data (even RX FIFO size). > For bigger chunks of data "AHB Read" is used. > > > > > If this is true - what was the rationale to use it in the new > > driver, as in the old one the "AHB Command Read" approach was > > recommended (i.e. faster) [1]? > > As explained above we only use "IP Read" for small chunks of data. To > speed up the tranfer for bigger chunks we do use "AHB Read". > And in the future we plan to add an interface for mapping memory, so > we can use the "AHB Read" even more efficiently. It looks like I do read the AHB internal QUADSPI buffer before it is filled up completely. (I've asked the NXP community support about it, but no reply so far https://community.nxp.com/thread/485139). > > > > > To be even more problematic the info in link [1] states that on > > vybrid there is a bug on the "IP Command Read" HW block and it > > should be avoided. > > If "IP Read" should be avoided completely for Vybrid, we have to add > some kind of quirk. Yes, I think so. According to the in-code comment the "IP Read" mode shall be avoided as it has some bugs. > > Thanks for you comments, > Frieder > > > > >>>>>> > >>>>>> I've googled for some errata or known issues for vybryd's QSPI > >>>>>> IP block (vf610) but without luck so far ... > >>>>> > >>>>> Unfortunately I don't know the background for this comment. > >>>> > >>>> The comment was added by some Freescale employee when the driver > >>>> was added to Linux (by Huang - CC'ed). > >>>> > >>>>> Is your > >>>>> board using VF610? > >>>> > >>>> Yes, it uses vf610 (A5 + M4 cores). > >>>> > >>>>> Do you experience problems? > >>>> > >>>> I've already observed following issue: > >>>> > >>>> For the current QSPI ML driver (fsl-quadspi.c - 4.19-rc3) only > >>>> half of the AHB buffer is valid. When I do read the whole one - > >>>> I do see read data corruption (on UBI or raw memory). > >>>> > >>>> This was pointed out in the patch: > >>>> https://patchwork.ozlabs.org/patch/675401/ > >>>> > >>>> Unfortunately, I did not found any info regarding this problem > >>>> (in NXP's errata or other doc). > >>>> > >>>> I will check if this issue shows up on new patches. > >>>> > >>>> Thanks in advance for your help. > >>>> > >>>>> > >>>>> Regards, > >>>>> Frieder > >>>>> > >>>>> ______________________________________________________ > >>>>> Linux MTD discussion mailing list > >>>>> http://lists.infradead.org/mailman/listinfo/linux-mtd/ > >>>> > >>>> Best regards, > >>>> > >>>> Lukasz Majewski > >>>> > >>>> -- > >>>> > >>>> DENX Software Engineering GmbH, Managing Director: Wolfgang > >>>> Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 > >>>> Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: > >>>> (+49)-8142-66989-80 Email: wd@xxxxxxx > >>> > >>> > >>> > >>> > >>> Best regards, > >>> > >>> Lukasz Majewski > >>> > >>> -- > >>> > >>> DENX Software Engineering GmbH, Managing Director: Wolfgang > >>> Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, > >>> Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: > >>> wd@xxxxxxx > >> > >> ______________________________________________________ > >> Linux MTD discussion mailing list > >> http://lists.infradead.org/mailman/listinfo/linux-mtd/ > > > > > > > > > > Best regards, > > > > Lukasz Majewski > > > > -- > > > > DENX Software Engineering GmbH, Managing Director: Wolfgang > > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, > > Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: > > wd@xxxxxxx Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@xxxxxxx
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