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@xxxxxxxxxxxxxx] > > > Sent: Thursday, March 23, 2017 10:44 PM > > > To: Shawn Guo > > > Cc: Fabio Estevam; A.S. Dong; devicetree@xxxxxxxxxxxxxxx; linux-arm- > > > kernel@xxxxxxxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; patchwork- > > > lst@xxxxxxxxxxxxxx > > > 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 <l.stach@xxxxxxxxxxxxxx> > > > --- > > > 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. Lothar Waßmann -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
