Am 27.04.2015 um 23:35 schrieb Ben Shelton: > I tested this against the latest version of the PL353 NAND driver that > Punnaiah > has been working to upstream (copying her on this message). With a few > changes > to that driver, I got it most of the way through initialization with on-die > ECC > enabled, but it segfaults here with a null pointer dereference because the > PL353 driver does not implement chip->cmd_ctrl. Instead, it implements a > custom override of cmd->cmdfunc that does not call cmd_ctrl. Looking through > the other in-tree NAND drivers, it looks like most of them do implement > cmd_ctrl, but quite a few of them do not (e.g. au1550nd, denali, docg4). > > What do you think would be the best way to handle this? It seems like this > gap > could be bridged from either side -- either the PL353 driver could implement > cmd_ctrl, at least as a stub version that provides the expected behavior in > this case; or the on-die framework could break this out into a callback > function with a default implementation that the driver could override to > perform this behavior in the manner of its choosing.
Oh, I thought every driver has to implement that function. ;-\ But you're right there is a corner case. What we could do is just using chip->cmdfunc() with a custom NAND command. i.e. chip->cmdfunc(mtd, NAND_CMD_READMODE, -1, -1); Gerhard Sittig tried to introduce such a command some time ago: http://lists.infradead.org/pipermail/linux-mtd/2014-April/053115.html Maybe Brian can bring some light into that too... > When I build this without CONFIG_MTD_NAND_ECC_ON_DIE enabled, I get the > following warning here: > > In file included from drivers/mtd/nand/nand_base.c:46:0: > include/linux/mtd/nand_ondie.h: In function 'nand_read_subpage_on_die': > include/linux/mtd/nand_ondie.h:28:1: warning: no return statement in function > returning non-void [-Wreturn-type] > include/linux/mtd/nand_ondie.h: In function 'nand_read_page_on_die': > include/linux/mtd/nand_ondie.h:34:1: warning: no return statement in function > returning non-void [-Wreturn-type] > > Perhaps return an error code here, even though you'll never get past the > BUG()? What gcc is this? gcc 4.8 here does not warn, I thought it is smart enough that this function does never return. Can it be that your .config has CONFIG_BUG=n? Anyway, this functions clearly needs a return statement. :) Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
