On Thu, Jan 22, 2015 at 11:59:37AM +0800, Robin Gong wrote: > Below comments got from Page4724 of Reference Manual of i.mx6q: > http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf > > --"Static context mode should be used for the first channel called > after reset to ensure that the all context RAM for that channel is > initialized during the context SAVE phase when the channel is > done or yields. Subsequent calls to the same channel or > different channels may use any of the dynamic context modes. > This will ensure that all context locations for the bootload > channel are initialized, and prevent undefined values in context > RAM from being loaded during the context restore if the > channel is re-started later" > > Unfortunately, the rule was broken by commit(5b28aa319bba96987316425a1131813d87cbab35) > .This patch just take them back. > > Signed-off-by: Robin Gong <b38343@xxxxxxxxxxxxx> > --- > drivers/dma/imx-sdma.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c > index d0df198..d84b7a8 100644 > --- a/drivers/dma/imx-sdma.c > +++ b/drivers/dma/imx-sdma.c > @@ -330,6 +330,8 @@ struct sdma_engine { > const struct sdma_driver_data *drvdata; > }; > > +static bool channel0_first; Nah, don't break the multi instance capability of drivers without a reason. Don't use global static variables in driver context. > + > static struct sdma_driver_data sdma_imx31 = { > .chnenbl0 = SDMA_CHNENBL0_IMX31, > .num_events = 32, > @@ -531,6 +533,12 @@ static int sdma_run_channel0(struct sdma_engine *sdma) > dev_err(sdma->dev, "Timeout waiting for CH0 ready\n"); > } > > + if (!channel0_first) { > + /* Set bits of CONFIG register with given context switching mode */ > + writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG); > + channel0_first = true; > + } You don't need a variable. How about: if (readl(sdma->regs + SDMA_H_CONFIG) == 0) writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG); Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
