Messages in this thread | | | Date | Fri, 11 Apr 2014 11:21:57 +0200 | From | Antoine Ténart <> | Subject | Re: [PATCH RESEND 2/5] pinctrl: berlin: add a pinctrl driver for Marvell Berlin SoCs |
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Jisheng,
On Fri, Apr 11, 2014 at 04:27:16PM +0800, Jisheng Zhang wrote: > Hi Antoine, > > On Fri, 11 Apr 2014 01:18:39 -0700 > Antoine Ténart <antoine.tenart@free-electrons.com> wrote: > > > Hi Jisheng, > > > > On Fri, Apr 11, 2014 at 02:44:31PM +0800, Jisheng Zhang wrote: > > > On Thu, 10 Apr 2014 06:07:51 -0700 > > > Antoine Ténart <antoine.tenart@free-electrons.com> wrote: > > > > > > ... > > > > +static int berlin_pinmux_enable(struct pinctrl_dev *pctrl_dev, > > > > + unsigned function, > > > > + unsigned group) > > > > +{ > > > > + struct berlin_pinctrl *pctrl = > > > > pinctrl_dev_get_drvdata(pctrl_dev); > > > > + struct berlin_pinctrl_group *group_desc = pctrl->groups + group; > > > > + struct berlin_pinctrl_function *function_desc = > > > > + pctrl->functions + function; > > > > + unsigned long flags; > > > > + u32 regval; > > > > + > > > > + spin_lock_irqsave(&pctrl->lock, flags); > > > > + > > > > + regval = readl(group_desc->reg); > > > > + regval &= group_desc->mask; > > > > + regval |= function_desc->muxval << group_desc->lsb; > > > > + writel(regval, group_desc->reg); > > > > > > Could we use relaxed version instead? > > > > We could, but this is not a performance issue here at all, so I guess we can > > keep writel(). > > Yes it's not a performance issue here but an issue for the system which is doing > PL310 L2 cache maintenance. If pinmux operation hold the l2x0_lock due to writel() > the important video/audio process which is cleaning PL310 cache must wait, thus > cause jitter. So I'd like relaxed version if we can. Then I don't need to add this > patch to mainline kernel when we upgrade internal tree.
I'm not sure I got that. As I understand it, you will need to play video/audio *while* configuring the pinmux. But the pinmuxing configuration is done at boot time, and I don't think a video/audio is being played then. So I'm not certain a jitter will appear. What do you think ?
Antoine
-- Antoine Ténart, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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