| Message ID | w3pboxz62q4.wl%kuninori.morimoto.gx@renesas.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, 15 Jun 2011, Kuninori Morimoto wrote: > Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com> > --- > drivers/dma/shdma.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c > index f7b3c06..19fd18d 100644 > --- a/drivers/dma/shdma.c > +++ b/drivers/dma/shdma.c > @@ -169,8 +169,9 @@ static void dmae_start(struct sh_dmae_chan *sh_chan) > { > u32 chcr = sh_dmae_readl(sh_chan, CHCR); > > + chcr &= ~CHCR_TE; > chcr |= CHCR_DE | CHCR_IE; > - sh_dmae_writel(sh_chan, chcr & ~CHCR_TE, CHCR); > + sh_dmae_writel(sh_chan, chcr, CHCR); > } Sorry, don't see any improvement here. The compiler will probably do the right thing for you and produce the same code, but strictly speaking you're asking it to do one more memory access - to store the result of your operation in the variable back on stack, instead of just keeping it in a register. On the contrary, you could even do u32 chcr = sh_dmae_readl(sh_chan, CHCR) & ~CHCR_TE; sh_dmae_writel(sh_chan, chcr | CHCR_DE | CHCR_IE, CHCR); to explicitly ask the compiler to avoid doing any unnecessary memory writes (we don't want to go the exaggerated "register" path;)). > > static void dmae_halt(struct sh_dmae_chan *sh_chan) > -- > 1.7.4.1 Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c index f7b3c06..19fd18d 100644 --- a/drivers/dma/shdma.c +++ b/drivers/dma/shdma.c @@ -169,8 +169,9 @@ static void dmae_start(struct sh_dmae_chan *sh_chan) { u32 chcr = sh_dmae_readl(sh_chan, CHCR); + chcr &= ~CHCR_TE; chcr |= CHCR_DE | CHCR_IE; - sh_dmae_writel(sh_chan, chcr & ~CHCR_TE, CHCR); + sh_dmae_writel(sh_chan, chcr, CHCR); } static void dmae_halt(struct sh_dmae_chan *sh_chan)
Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com> --- drivers/dma/shdma.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)