On Wed, 01 Apr 2015, Joe Perches wrote: > On Wed, 2015-04-01 at 10:08 -0500, Aaron Sierra wrote: > > ----- Original Message ----- > > > From: "Nicholas Mc Guire" <der.h...@hofr.at> > > > Sent: Wednesday, April 1, 2015 9:24:44 AM > > > > > > On Wed, 01 Apr 2015, Aaron Sierra wrote: > > > > > > > ----- Original Message ----- > > > > > From: "Nicholas Mc Guire" <hof...@osadl.org> > > > > > Sent: Friday, March 13, 2015 6:23:47 AM > > > > > > > > > > This is only an API consolidation and should make things more readable > > > > > it replaces var * HZ / 1000 by msecs_to_jiffies(var) which helps > > > > > readability > > > > > and also handles all corner-cases properly. > > > > > > > > > > Signed-off-by: Nicholas Mc Guire <hof...@osadl.org> > > > > > --- > > > > > > > > > > Patch was compile tested with corenet64_smp_defconfig > > > > > (implies CONFIG_MTD_NAND_FSL_IFC=y) > > > > > > > > > > Patch is against 4.0-rc3 (localversion-next is -next-20150313 > > > > > > > > > > drivers/mtd/nand/fsl_ifc_nand.c | 4 ++-- > > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/mtd/nand/fsl_ifc_nand.c > > > > > b/drivers/mtd/nand/fsl_ifc_nand.c > > > > > index 4c05f4f..51394e5 100644 > > > > > --- a/drivers/mtd/nand/fsl_ifc_nand.c > > > > > +++ b/drivers/mtd/nand/fsl_ifc_nand.c > > > > > @@ -317,7 +317,7 @@ static void fsl_ifc_run_command(struct mtd_info > > > > > *mtd) > > > > > > > > > > /* wait for command complete flag or timeout */ > > > > > wait_event_timeout(ctrl->nand_wait, ctrl->nand_stat, > > > > > - IFC_TIMEOUT_MSECS * HZ/1000); > > > > > + msecs_to_jiffies(IFC_TIMEOUT_MSECS)); > > > > > > > > Nicholas, > > > > Your patch makes me think that this timeout value should be calculated > > > > once during initialization and stored in a new member of > > > > struct fsl_ifc_mtd. That would improve readability AND have some > > > > positive impact on performance. > > > > > > > > > > is it not a bit wasteful to put it into struct fsl_ifc_mtd > > > which is used quite often in here ?cho > > > > Storing the timeout in the private structure would use 4 or 8 bytes, > > but the structure is passed around as pointer reference, so there is > > no added overhead there. > > > > > #define IFC_TIMEOUT msecs_to_jiffies(500) > > > > > > sould do - its only referenced twice and would achieve what you > > > suggested - initializing it in one location and improved readability > > > > > > wait_event_timeout(ctrl->nand_wait, ctrl->nand_stat, IFC_TIMEOUT); > > > > > > would there be any disadvantage of this solution? > > > > I don't have an issue with the compactness of your code. The issue > > to me is that msecs_to_jiffies() is a real function call, not a macro. > > That means that there would be a branch to that function followed by a > > non-trivial calculation *every* time fsl_ifc_run_command() is called. > > > > If the timeout value were calculated during init, then the cost of > > accessing it would simply a pointer dereference. > > Nicholas, any progress on that builtin_const_p variant > did not get to it yet - but thats the next thing on my fun list.
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