| Message ID | 200912081301.25597.jbe@pengutronix.de |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Dec 08, 2009 at 01:01:25PM +0100, Juergen Beisert wrote: > When unmounting an mtd filesystem the s3c2410_nand_select_chip() function > gets called again with "chip == -1". In this case the current code disables > the NFC clock at least a second time, so it does not work anymore. > Clock disabling should only happen if it was really enabled. > > Due to a lack of a query function if a clock is already enabled (and how often), > we must count enable/disable calls by our own here. > > Note: Other enable/disable sequences can be found in the power management > functions. I'm not sure if they interfere with this local enable/disable count. > > Signed-off-by: Juergen Beisert <jbe@pengutronix.de> > Acked-by: Wolfram Sang <wsa@pengutronix.de> > > --- > drivers/mtd/nand/s3c2410.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > Index: linux-2.6.32/drivers/mtd/nand/s3c2410.c > =================================================================== > --- linux-2.6.32.orig/drivers/mtd/nand/s3c2410.c > +++ linux-2.6.32/drivers/mtd/nand/s3c2410.c > @@ -329,12 +329,15 @@ static void s3c2410_nand_select_chip(str > struct s3c2410_nand_mtd *nmtd; > struct nand_chip *this = mtd->priv; > unsigned long cur; > + static int clock_enable_cnt = 0; It probably does not matter a lot, since there seem to be only one nand controller and associated clock per system, but it would be cleaner to move this variable into struct s3c2410_nand_info to allow this driver eventually service multiple instances of nand controller. > nmtd = this->priv; > info = nmtd->info; > > - if (chip != -1 && allow_clk_stop(info)) > + if (chip != -1 && allow_clk_stop(info)) { > clk_enable(info->clk); > + clock_enable_cnt++; > + } > > cur = readl(info->sel_reg); > > @@ -356,8 +359,10 @@ static void s3c2410_nand_select_chip(str > > writel(cur, info->sel_reg); > > - if (chip == -1 && allow_clk_stop(info)) > + if (chip == -1 && allow_clk_stop(info) && clock_enable_cnt > 0) { > clk_disable(info->clk); > + clock_enable_cnt--; > + } > } > > /* s3c2410_nand_hwcontrol > > -- > Pengutronix e.K. | Juergen Beisert | > Linux Solutions for Science and Industry | Phone: +49-8766-939 228 | > Vertretung Sued/Muenchen, Germany | Fax: +49-5121-206917-5555 | > Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de/ | > > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/
Index: linux-2.6.32/drivers/mtd/nand/s3c2410.c =================================================================== --- linux-2.6.32.orig/drivers/mtd/nand/s3c2410.c +++ linux-2.6.32/drivers/mtd/nand/s3c2410.c @@ -329,12 +329,15 @@ static void s3c2410_nand_select_chip(str struct s3c2410_nand_mtd *nmtd; struct nand_chip *this = mtd->priv; unsigned long cur; + static int clock_enable_cnt = 0; nmtd = this->priv; info = nmtd->info; - if (chip != -1 && allow_clk_stop(info)) + if (chip != -1 && allow_clk_stop(info)) { clk_enable(info->clk); + clock_enable_cnt++; + } cur = readl(info->sel_reg); @@ -356,8 +359,10 @@ static void s3c2410_nand_select_chip(str writel(cur, info->sel_reg); - if (chip == -1 && allow_clk_stop(info)) + if (chip == -1 && allow_clk_stop(info) && clock_enable_cnt > 0) { clk_disable(info->clk); + clock_enable_cnt--; + } } /* s3c2410_nand_hwcontrol