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SubjectRe: [PATCH v1 5/7] soc: mediatek: add a fixed wait for SRAM stable
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On Fri, 2018-04-20 at 11:49 +0800, Sean Wang wrote:
> On Thu, 2018-04-19 at 12:33 +0200, Matthias Brugger wrote:
> >
> > On 04/03/2018 09:15 AM, sean.wang@mediatek.com wrote:
> > > From: Sean Wang <sean.wang@mediatek.com>
> > >
> > > MT7622_POWER_DOMAIN_WB doesn't send an ACK when its managed SRAM becomes
> > > stable, which is not like the behavior the other power domains should
> > > have. Therefore, it's necessary for such a power domain to have a fixed
> > > and well-predefined duration to wait until its managed SRAM can be allowed
> > > to access by all functions running on the top.
> > >
> > > Signed-off-by: Sean Wang <sean.wang@mediatek.com>
> > > Cc: Matthias Brugger <matthias.bgg@gmail.com>
> > > Cc: Ulf Hansson <ulf.hansson@linaro.org>
> > > Cc: Weiyi Lu <weiyi.lu@mediatek.com>
> > > ---
> > > drivers/soc/mediatek/mtk-scpsys.c | 17 ++++++++++++-----
> > > 1 file changed, 12 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
> > > index f9b7248..19aceb8 100644
> > > --- a/drivers/soc/mediatek/mtk-scpsys.c
> > > +++ b/drivers/soc/mediatek/mtk-scpsys.c
> > > @@ -121,6 +121,7 @@ struct scp_domain_data {
> > > u32 bus_prot_mask;
> > > enum clk_id clk_id[MAX_CLKS];
> > > bool active_wakeup;
> > > + u32 us_sram_fwait;
> >
> > Before adding more and more fields to scp_domain_data which get checked in if's,
> > I'd prefer to add a caps field used for bus_prot_mask, active_wakeup in a first
> > patch and add the cap FORCE_WAIT in a second patch.
> >
> > Can you help to implement this Sean, or shall I give it a try?
> >
>
> Sure, I have a willing to do and then see if you're also fond of it.
>
> thanks!
>

Hi, Matthias

I have done it in [1], but in the version, I doesn't merge bus_prot_mask
into caps fields because bus_prot_mask is actually mapped into realistic
hardware bitmap like sram_pdn_bits, sram_pdn_ack_bits, sta_mask is
doing.

It should be more straightforward to port a new SoC to scpsys when there
are standalone fields to hold these hardware configuring bitmaps.

[1]
http://lists.infradead.org/pipermail/linux-mediatek/2018-April/012884.html

Sean

> > Regards,
> > Matthias
> >
> > > };
> > >
> > > struct scp;
> > > @@ -234,11 +235,16 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
> > > val &= ~scpd->data->sram_pdn_bits;
> > > writel(val, ctl_addr);
> > >
> > > - /* wait until SRAM_PDN_ACK all 0 */
> > > - ret = readl_poll_timeout(ctl_addr, tmp, (tmp & pdn_ack) == 0,
> > > - MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> > > - if (ret < 0)
> > > - goto err_pwr_ack;
> > > + /* Either wait until SRAM_PDN_ACK all 0 or have a force wait */
> > > + if (!scpd->data->us_sram_fwait) {
> > > + ret = readl_poll_timeout(ctl_addr, tmp, (tmp & pdn_ack) == 0,
> > > + MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> > > + if (ret < 0)
> > > + goto err_pwr_ack;
> > > + } else {
> > > + usleep_range(scpd->data->us_sram_fwait,
> > > + scpd->data->us_sram_fwait + 100);
> > > + };
> > >
> > > if (scpd->data->bus_prot_mask) {
> > > ret = mtk_infracfg_clear_bus_protection(scp->infracfg,
> > > @@ -783,6 +789,7 @@ static const struct scp_domain_data scp_domain_data_mt7622[] = {
> > > .clk_id = {CLK_NONE},
> > > .bus_prot_mask = MT7622_TOP_AXI_PROT_EN_WB,
> > > .active_wakeup = true,
> > > + .us_sram_fwait = 12000,
> > > },
> > > };
> > >
> > >
>


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