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Date: Fri, 23 Sep 2016 13:29:44 +0200
From: Jan Glauber <jan.glauber@caviumnetworks.com>
To: <linux-mtd@lists.infradead.org>
Subject: Question about nand_scan()
Message-ID: <20160923112944.GB4580@hardcore>
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Hi all,

I'm working on a driver for the NAND controller on Cavium's ThunderX.

So far I implemented the low-level functions for using the controller
to access a NAND chip. I can read the ONFI ID and parameter page
with that.

Now I wanted to use nand_scan() instead of manually reading the chip
parameters, but it fails with "No NAND device found".

The hardware I'm using has one NAND device wired as chip 1 (the NAND
controller support chips 0..7).

The reason for the failure seems to be that nand_get_flash_type()
returns an error before all the chips are scanned. What I don't
understand is in that function chip 0 is selected before the loop
that would scan all chips:

        /* Select the device */
        chip->select_chip(mtd, 0);

My select_chip() stores the chip number (in that case 0) and uses
that for subsequent commands to the controller. Since there is no
chip 0 the read returns nothing and nand_scan() fails.

Probably I'm missing something, would be great if someone could
help me...

thanks,
Jan