mirror of
https://github.com/torvalds/linux.git
synced 2024-12-23 19:31:53 +00:00
009e7e61b1
Support for the Macronix 32-bit addressing scheme was originally developed using the MX25L25635E device. As is often the case, it was found that the presence of a "WAIT" instruction was required for the "EN4B/EX4B" FSM Sequence to complete. (It is known that the SPI FSM Controller makes certain undocumented assumptions regarding what constitutes a valid sequence.) However, further testing suggested that a small delay was required after issuing the "EX4B" command; without this delay, data corruptions were observed, consistent with the device not being ready to retrieve data. Although the issue was not fully understood, the workaround of adding a small delay was implemented, while awaiting clarification from Macronix. The same behaviour has now been found with a second Macronix device, the MX25L25655E. However, with this device, it seems that the delay is also required after the 'EN4B' commands. This discovery has prompted us to revisit the issue. Although still not conclusive, further tests have suggested that the issue is down to the SPI FSM Controller, rather than the Macronix devices. Furthermore, an alternative workaround has emerged which is to set the WAIT time to 0x00000001, rather then 0x00000000. (Note, the WAIT instruction is used purely for the purpose of achieving "sequence validity", rather than actually implementing a delay!) The issue is now being investigated by the Design and Validation teams. In the meantime, we implement the alternative workaround, which reduces the effective delay from 1us to 1ns. Signed-off-by: Angus Clark <angus.clark@st.com> Signed-off-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Brian Norris <computersforpeace@gmail.com> |
||
|---|---|---|
| .. | ||
| bcm47xxsflash.c | ||
| bcm47xxsflash.h | ||
| block2mtd.c | ||
| docg3.c | ||
| docg3.h | ||
| elm.c | ||
| Kconfig | ||
| lart.c | ||
| m25p80.c | ||
| Makefile | ||
| ms02-nv.c | ||
| ms02-nv.h | ||
| mtd_dataflash.c | ||
| mtdram.c | ||
| phram.c | ||
| pmc551.c | ||
| serial_flash_cmds.h | ||
| slram.c | ||
| spear_smi.c | ||
| sst25l.c | ||
| st_spi_fsm.c | ||