Hello Jagan,
-----Original Message----- From: Bin Meng bmeng.cn@gmail.com Sent: Wednesday, February 19, 2020 9:59 PM To: Sagar Kadam sagar.kadam@sifive.com Cc: U-Boot Mailing List u-boot@lists.denx.de; Rick Chen rick@andestech.com; Paul Walmsley ( Sifive) paul.walmsley@sifive.com; Jagan Teki jagan@amarulasolutions.com; Anup Patel anup.patel@wdc.com Subject: Re: [U-Boot Patch v2 3/4] dts: u-boot.dtsi: override flash tx-rx width
Hi Sagar,
On Fri, Feb 7, 2020 at 2:43 AM Sagar Kadam sagar.kadam@sifive.com wrote:
Hello Bin,
-----Original Message----- From: Bin Meng bmeng.cn@gmail.com Sent: Tuesday, February 4, 2020 5:43 PM To: Sagar Kadam sagar.kadam@sifive.com Cc: U-Boot Mailing List u-boot@lists.denx.de; Rick Chen rick@andestech.com; Paul Walmsley ( Sifive) paul.walmsley@sifive.com; Jagan Teki
Anup Patel anup.patel@wdc.com Subject: Re: [U-Boot Patch v2 3/4] dts: u-boot.dtsi: override flash tx-rx width
Hi Sagar,
On Wed, Jan 29, 2020 at 2:02 AM Sagar Shrikant Kadam sagar.kadam@sifive.com wrote:
The hifive-unleashed-a00.dts has flash spi-tx/rx width set to 4-bit mode. During sf probe, spi_nor_scan fails to read the JEDEC ID with reg_proto set to SNOR_PROTO_1_1_1. Setting it to 1-bit mode as of now will help read the JEDEC-ID and perform other flash
operations.
So previously with Jagan's series that did not have these changes in this commit, the flash driver worked well. I wonder what real issue was fixed in this commit?
Yes true, I had observed that flash device was working with Jagan's series you are indicating here. The flash device was getting probed at cs
2/4/6/8 etc..
but it couldn't get detected on CS0 which is actually connected on the board to the flash device. With the check of spi->num_cs done in patch 2 of this series or the one handled in commit 7bacce524d48 ("dm: spi: Check cs number before accessing slaves") invalid chip select is taken care of and flash is not detected on wrong chip selects, but spi transfer still fails as the sifive-spi driver set's the SIFIVE_SPI_FMT_PROTO_QUAD mode based on device tree information. While reading Device ID in spi_nor_scan the reg proto is set to 1_1_1 bit mode and this contradicts here in the driver
due to which spi_nor_scan fails, due to which one cannot use the flash.
So for now I have added this override here to 1 bit mode so that users can
use it.
Maybe I will update the commit message to indicate that this is workaround for a bug in SPI driver for FU540 which currently is not able to
handle QUAD mode operation.
Please let me know your views here.
Thanks for the details. Based on your description, I think there is something wrong with the SPI-NOR driver. Your change to 1 line only seems to be a workaround.
Jagan, would you please comment?
It would be good if you could also share some input's here.
Thanks & BR, Sagar Kadam
Regards, Bin