Commit 49aa76b166 ("mtd: rawnand: do not execute nand_scan_ident()
if maxchips is zero") gave a new meaning for calling nand_scan_ident()
with maxchips=0.
It is a special usage for some drivers such as docg4, but actually
the Denali driver may pass maxchips=0 to nand_scan() when the driver
is enabled but no NAND chip is found on the board for some reasons.
If nand_scan_with_ids() is called with maxchips=0, nand_scan_ident()
is skipped, then nand_set_defaults() is skipped as well. Thus, the
driver must set chip->controller beforehand. Otherwise, nand_attach()
causes NULL pointer dereference.
In fact, the Denali controller knows the number of connected chips
before calling nand_scan_ident(); if DEVICE_RESET fails, there is no
chip in that chip select. Then, denali_reset_banks() sets the maxchips
to the number of detected chips. If no chip is found, maxchips is zero.
In this case, there is no point for calling nand_scan() because we know
it will fail for sure. Let's make the probe function fail immediately.
Fixes: 49aa76b166 ("mtd: rawnand: do not execute nand_scan_ident() if maxchips is zero")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
336d139f87