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

Matthias Brugger
2018-04-23T09:31:36Z

On 04/23/2018 10:36 AM, sean.wang at 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.
>
> 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.
> + */

I would say, if necessary in the future we can add a switch statement here.
Other then that the patches look good. If you are OK, I'll just delete the last
sentence when applying the patch.

Regards,
Matthias

> + 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,
> },
> };
>
>