[PATCH v2 2/2] soc: mediatek: add a fixed wait for SRAM stable

sean.wang at mediatek.com
2018-04-23T08:36:22Z

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.

v1 -> v2:
- use MTK_SCPD_FWAIT_SRAM flag as an indication requiring force waiting.

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 | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
index b1b45e4..d4f1a63 100644
--- a/drivers/soc/mediatek/mtk-scpsys.c
+++ b/drivers/soc/mediatek/mtk-scpsys.c
@@ -32,6 +32,7 @@
#define MTK_POLL_TIMEOUT (jiffies_to_usecs(HZ))

#define MTK_SCPD_ACTIVE_WAKEUP BIT(0)
+#define MTK_SCPD_FWAIT_SRAM BIT(1)
#define MTK_SCPD_CAPS(_scpd, _x) ((_scpd)->data->caps & (_x))

#define SPM_VDE_PWR_CON 0x0210
@@ -237,11 +238,22 @@ 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 (!MTK_SCPD_CAPS(scpd, MTK_SCPD_FWAIT_SRAM)) {
+ 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 {
+ /*
+ * Currently, MTK_SCPD_FWAIT_SRAM is necessary only for
+ * MT7622_POWER_DOMAIN_WB and thus just a trivial setup is
+ * applied here. If there're more domains which need to force
+ * waiting for its own pre-defined value, the duration should
+ * be coded in the caps field.
+ */
+ usleep_range(12000, 12100);
+ };

if (scpd->data->bus_prot_mask) {
ret = mtk_infracfg_clear_bus_protection(scp->infracfg,
@@ -785,7 +797,7 @@ static const struct scp_domain_data scp_domain_data_mt7622[] = {
.sram_pdn_ack_bits = 0,
.clk_id = {CLK_NONE},
.bus_prot_mask = MT7622_TOP_AXI_PROT_EN_WB,
- .caps = MTK_SCPD_ACTIVE_WAKEUP,
+ .caps = MTK_SCPD_ACTIVE_WAKEUP | MTK_SCPD_FWAIT_SRAM,
},
};

--
2.7.4