On Mon, 2019-03-25 at 22:36 +0530, Vignesh Raghavendra wrote: > > On 25/03/19 7:21 PM, Joakim Tjernlund wrote: > > On Mon, 2019-03-25 at 18:27 +0530, Vignesh Raghavendra wrote: > > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. > > > > > > > > > Hi, > > > > > > On 21/03/19 11:41 PM, Joakim Tjernlund wrote: > > > > On Thu, 2019-03-21 at 23:15 +0530, Vignesh Raghavendra wrote: > > > > > HyperFlash devices are compliant with CFI AMD/Fujitsu Extended Command > > > > > Set(0x0002) for flash operations, therefore drivers/mtd/chips/cfi_cmdset_0002.c > > > > > can be use as is. But these devices do not support DQ polling method of > > > > > determining chip ready/good status. These flashes provide Status > > > > > Register whose bits can be polled to know status of flash operation. > > > > > > > > > > Cypress HyperFlash datasheet here[1], talks about CFI Amd/Fujitsu > > > > > Extended Query version 1.5. Bit 0 of "Software Features supported" field > > > > > of CFI Primary Vendor-Specific Extended Query table indicates > > > > > presence/absence of status register and Bit 1 indicates whether or not > > > > > DQ polling is supported. Using these bits, its possible to determine > > > > > whether flash supports DQ polling or need to use Status Register. > > > > > > > > > > Add support for polling status register to know device ready/status of > > > > > erase/write operations when DQ polling is not supported. > > > > > > > > Isn't this new Status scheme just a copy of Intels(cmdset_0001)? > > > > > > Yes, but with one difference: At the end of program/erase operation, > > > device directly enters status register mode and starts reflecting > > > status register content at any address. > > > The device remains in the read status register state until another > > > command is written to the device. Therefore there is notion of device is > > > in "status register read mode" (FL_STATUS) state > > > > That seems to vary and long time ago RMK added this: > > /* If the flash has finished erasing, then 'erase suspend' > > * appears to make some (28F320) flash devices switch to > > * 'read' mode. Make sure that we switch to 'read status' > > * mode so we get the right data. --rmk > > */ > > map_write(map, CMD(0x70), chip->in_progress_block_addr); > > > > This behavior is expected with cmdset_0001. Because "The device remains > in the read status register state until another command is written", > therefore "erase suspend' command after erase completion will switch > device to read mode. And therefore read status is safe thing to do for > cmdset_0001. > > But in case of cmdset_0002 erase completion will not put device to read > status mode and therefore no special status tracking is required. > > > > But in case of cfi_cmdset_0002, once program/erase operation is > > > complete, device returns to previous address space overlay from which > > > operation was started from (mostly read mode) > > > > I hope you can do the same as Intel here, issue an explicit Status CMD or you will be in trouble. > > Even if we issue Read Status command to enter read status mode, any > single subsequent read will put device back to read mode. So, sending > explicit Status CMD is of not much use. > > As long as cmdset_0002 driver ensures sending Read Status cmd and next > single read can be done in one go (ie. mutex held), I don't see any > trouble here. This is already take care off. Ouch, a non sticky Status sounds borken. Are you sure that nothing can change the chip between you issue the Status CMD and read out of status bits? Like if an erase/suspend/resume completes just after Status CMD but before Status readout? Jocke > > > Also, I think you need to use the various map_word_xxx as in: > > status = map_read(map, chip->in_progress_block_addr); > > if (map_word_andequal(map, status, status_OK, status_OK)) > > break; > > Yes, I will fixup this patch to use map_word_* wherever necessary in the > next revision. > > > > otherwise you will break interleaved setups(like two 8-bit flashes in parallel to > > form one 16 bit bus). Maybe this is not supported for CMDSET 0002 ? > > > > Interleaved is indeed supported by cmdset_0002. Thanks for pointing that > out! > > > Jocke > > > > > In order to enter status register overlay mode, Read Status command is > > > to be written to addr_unlock1(0x555) address. The overlay is in effect > > > for one read access, specifically the next read access that follows the > > > Status Register Read command > > > Therefore code around FL_STATUS state in cfi_cmdset_0001 is not > > > applicable to cfi_cmdset_0002 as is. > > > > > > > > > > If so I think the new status impl. in 0002 should borrow from 0001 as this is a > > > > hardened and battle tested impl. > > > > > > > > > > In case of cfi_cmdset_0001.c, program/erase is followed by > > > inval_cache_and_wait_for_operation() to poll ready bit and based on > > > status register value, success or the error handling is done. > > > > > > Most of the code corresponding to inval_cache_and_wait_for_operation() > > > is already in cfi_cmdset_0002.c. So, whats missing in this patch is > > > handling and reporting of errors as reflected in status register after > > > write/erase failures. I will add that in the next version. > > > > > > But, I don't see much to borrow apart from error handling sequence. > > > Please, let me know if I missed something. > > > > > > > I know other modern 0002 chips supports both old and new impl. of Status and I world > > > > guess that we will see more chips with new Status only. > > > > > > > > > > Agreed. Newer devices would mostly be CFI 1.5. > > > > > > -- > > > Regards > > > Vignesh
