> -----Original Message----- > From: York Sun > Sent: Thursday, October 25, 2018 9:20 PM > To: Stefan Roese <s...@denx.de> > Cc: u-boot@lists.denx.de; Jagan Teki <ja...@openedev.com>; Rajat > Srivastava <rajat.srivast...@nxp.com>; simon.k.r.goldschm...@gmail.com; > Ashish Kumar <ashish.ku...@nxp.com> > Subject: Re: [U-Boot] [PATCH v3] sf: Add auto detection of 4-byte mode (vs > standard 3-byte mode) > > Guys, > > Let get back to the original thread. Since Rajat's first reply, the > message id has been changed. All the comments were not captured by > patchwork. > > On 10/11/18 07:50, Stefan Roese wrote: > > Some SPI NOR chips only support 4-byte mode addressing. Here the > default > > 3-byte mode does not work and leads to incorrect accesses. This patch > > now reads the 4-byte mode status bit (in this case in the CR register > > of the Macronix SPI NOR) and configures the SPI transfers accordingly. > > > > This was noticed on the LinkIt Smart 7688 modul, which is equipped with > > an Macronix MX25L25635F device. But this device does *NOT* support > > switching to 3-byte mode via the EX4B command. > > > > This should also work when the bootrom configures the SPI flash to > > 4-byte mode and runs U-Boot after this. U-Boot should dectect this > > mode (if the 4-byte mode detection is available for this chip) and > > use the correct OPs in this case. > > From what I read, Rajat's method is to extend the controller driver to > support read SFDP and default to 4-byte mode if supported, or > overwritten by user's flag. Stefan's method is to read 4-byte status bit > and doesn't change controller driver. > > Is the default value of this 4-byte status bit valid and correct for all > cases? > > Rajat, without your patch set, does Stefan's solution work for your board? > > York
No. Stefan's changes are specific to his boards and is not applicable on ours. Stefan's patch is to support only certain flash that are factory strapped to work in 4-byte addressing modes only and will default to old method if such a flash is not found. The flashes on our boards (and also other vendor's board) will not work with Stefan's patch. My patch can handle flashes with address widths of 3-byte, 4-byte or both. It also takes a more generic path (as opposed to supporting only specific flash models) by parsing SFDP standard parameters and then deciding what address width is to be used. - Rajat _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
