[FS#1120] Newifi D1 - Unable to reboot

[LEDE Bugs]

The following task has a new comment added:

FS#1120 - Newifi D1 - Unable to reboot
User who did this - Mathias Kresin (mkresin)

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@easyteacher We are talking about different topics. Backporting 4-byte mode to 17.04. will be most likely not accepted.

Furthermore, there was a "fix" which sets some register values for all SPI flash chips (was either exit 4-byte mode or a chip reset, can't remember). It is a no go as well.

My NAK wasn't for your SPI_NOR_4B_READ_OP approach, which I obviously missed when I had a look at the forum topic.

Nevertheless, I'm kind of surprised that SPI_NOR_4B_READ_OP is supposed to work with the MX25L25635E. The [[http://www.macronix.com/Lists/Datasheet/Attachments/6639/MX25L25635E,%203V,%20256Mb,%20v1.3.pdf|MX25L25635E datasheet]] doesn't mention a stateless 4-byte read command (see table 5 "command sets"), where the [[https://www.winbond.com/resource-files/w25q256fv_revg1_120214_qpi_website_rev_g.pdf|W25Q256 datasheet]] does (Read Data with 4-Byte Address [13h]).

In fact, the MX25L25635E datasheet says:

> The default read mode is 3-byte address, to access higher address (4-byte address) which requires to enter the 4-byte address read mode...

Entering the 4-byte mode is stateful and exactly the reason for the reboot hang. Since support isn't mentioned in the datasheet, SPI_NOR_4B_READ_OP isn't enabled for the MX25L25635E.
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More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1120#comment4631