From: Lucas Stach <l.stach@pengutronix.de>
To: "Lothar Waßmann" <LW@KARO-electronics.de>
Cc: "A.S. Dong" <aisheng.dong@nxp.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"patchwork-lst@pengutronix.de" <patchwork-lst@pengutronix.de>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
Fabio Estevam <fabio.estevam@nxp.com>,
Shawn Guo <shawnguo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/2] soc/imx: add workaround for i.MX6QP to the GPC PD driver
Date: Thu, 30 Mar 2017 10:22:17 +0200 [thread overview]
Message-ID: <1490862137.29083.30.camel@pengutronix.de> (raw)
In-Reply-To: <20170330090833.09ac3c33@ipc1.ka-ro>
Am Donnerstag, den 30.03.2017, 09:08 +0200 schrieb Lothar Waßmann:
> 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@pengutronix.de]
> > > > Sent: Thursday, March 23, 2017 10:44 PM
> > > > To: Shawn Guo
> > > > Cc: Fabio Estevam; A.S. Dong; devicetree@vger.kernel.org; linux-arm-
> > > > kernel@lists.infradead.org; kernel@pengutronix.de; patchwork-
> > > > lst@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 <l.stach@pengutronix.de>
> > > > ---
> > > > 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
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
prev parent reply other threads:[~2017-03-30 8:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 14:44 [PATCH 0/2] i.MX6QP GPC fixes Lucas Stach
[not found] ` <20170323144418.30977-1-l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2017-03-23 14:44 ` [PATCH 1/2] dt-bindings: imx-gpc: add i.MX6 QuadPlus compatible Lucas Stach
[not found] ` <20170323144418.30977-2-l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2017-03-29 15:59 ` Rob Herring
2017-03-23 14:44 ` [PATCH 2/2] soc/imx: add workaround for i.MX6QP to the GPC PD driver Lucas Stach
[not found] ` <20170323144418.30977-3-l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2017-03-24 6:28 ` Shawn Guo
2017-03-29 16:08 ` A.S. Dong
[not found] ` <DB5PR04MB1431A7CC91F55ECFE5BE31FB80350-rqLcZCCNzVwrYIBjo4yUUM9NdZoXdze2vxpqHgZTriW3zl9H0oFU5g@public.gmane.org>
2017-03-29 16:13 ` Lucas Stach
2017-03-30 7:08 ` Lothar Waßmann
2017-03-30 8:22 ` Lucas Stach [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1490862137.29083.30.camel@pengutronix.de \
--to=l.stach@pengutronix.de \
--cc=LW@KARO-electronics.de \
--cc=aisheng.dong@nxp.com \
--cc=devicetree@vger.kernel.org \
--cc=fabio.estevam@nxp.com \
--cc=kernel@pengutronix.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=patchwork-lst@pengutronix.de \
--cc=shawnguo@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).