From mboxrd@z Thu Jan 1 00:00:00 1970 From: l.stach@pengutronix.de (Lucas Stach) Date: Thu, 30 Mar 2017 10:22:17 +0200 Subject: [PATCH 2/2] soc/imx: add workaround for i.MX6QP to the GPC PD driver In-Reply-To: <20170330090833.09ac3c33@ipc1.ka-ro> References: <20170323144418.30977-1-l.stach@pengutronix.de> <20170323144418.30977-3-l.stach@pengutronix.de> <1490804026.29083.29.camel@pengutronix.de> <20170330090833.09ac3c33@ipc1.ka-ro> Message-ID: <1490862137.29083.30.camel@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am Donnerstag, den 30.03.2017, 09:08 +0200 schrieb Lothar Wa?mann: > Hi, > > On Wed, 29 Mar 2017 18:13:46 +0200 Lucas Stach wrote: > > Am Mittwoch, den 29.03.2017, 16:08 +0000 schrieb A.S. Dong: > > > Hi Lucas, > > > > > > > -----Original Message----- > > > > From: Lucas Stach [mailto:l.stach at pengutronix.de] > > > > Sent: Thursday, March 23, 2017 10:44 PM > > > > To: Shawn Guo > > > > Cc: Fabio Estevam; A.S. Dong; devicetree at vger.kernel.org; linux-arm- > > > > kernel at lists.infradead.org; kernel at pengutronix.de; patchwork- > > > > lst at pengutronix.de > > > > Subject: [PATCH 2/2] soc/imx: add workaround for i.MX6QP to the GPC PD > > > > driver > > > > > > > > On i.MX6QP, due to hardware erratum ERR009619, the PRE clocks may be > > > > stalled during the power up sequencing of the PU power domain. As this may > > > > lead to a complete loss of display output, the recommended workaround is > > > > to keep the PU domain enabled during normal system operation. > > > > > > > > Implement this by rejecting the domain power down request on the affected > > > > SoC. > > > > > > > > Signed-off-by: Lucas Stach > > > > --- > > > > drivers/soc/imx/gpc.c | 19 +++++++++++++++++++ > > > > 1 file changed, 19 insertions(+) > > > > > > > > diff --git a/drivers/soc/imx/gpc.c b/drivers/soc/imx/gpc.c index > > > > 4294287e5f6c..599e1e46f694 100644 > > > > --- a/drivers/soc/imx/gpc.c > > > > +++ b/drivers/soc/imx/gpc.c > > > > @@ -45,6 +45,7 @@ struct imx_pm_domain { > > > > unsigned int reg_offs; > > > > signed char cntr_pdn_bit; > > > > unsigned int ipg_rate_mhz; > > > > + bool allow_dynamic_pd; > > > > }; > > > > > > > > static inline struct imx_pm_domain * > > > > @@ -59,6 +60,9 @@ static int imx6_pm_domain_power_off(struct > > > > generic_pm_domain *genpd) > > > > int iso, iso2sw; > > > > u32 val; > > > > > > > > + if (!pd->allow_dynamic_pd) > > > > + return -EBUSY; > > > > + > > > > /* Read ISO and ISO2SW power down delays */ > > > > regmap_read(pd->regmap, pd->reg_offs + GPC_PGC_PUPSCR_OFFS, &val); > > > > iso = val & 0x3f; > > > > @@ -255,6 +259,7 @@ static struct imx_pm_domain imx_gpc_domains[] = { > > > > }, > > > > .reg_offs = 0x260, > > > > .cntr_pdn_bit = 0, > > > > + .allow_dynamic_pd = true, > > > > }, { > > > > .base = { > > > > .name = "DISPLAY", > > > > @@ -263,23 +268,33 @@ static struct imx_pm_domain imx_gpc_domains[] = { > > > > }, > > > > .reg_offs = 0x240, > > > > .cntr_pdn_bit = 4, > > > > + .allow_dynamic_pd = true, > > > > > > Just a Nitpick, besides shawn's comment in another mail, > > > if we use a domain flag like IMX_PD_ALWAYS_ON set by SoC errata flag, > > > then probably we can save all the default allow_dynamic_pd lines. > > > This also release the life when adding new domains. > > > > If other things like that show up we can certainly switch to a flags > > field. In the meantime I like that the current style is more explicit > > about it. > > > Since the purpose of the driver is all about dynamic power management, > I would rather add a 'disable_dynamic_pd' for the case(s) where it's > not allowed, rather than having to state the obvious over and over > again. Convincing argument. I'll change that in v2. Regards, Lucas