From: Venkateswara Rao Mandela venkat.mandela@ti.com
Description of DRA7 Errata i932:
In rare circumstances DPLL_VIDEO1 and DPLL_VIDEO2 PLL's may not lock on the first attempt during DSS initialization. When this occurs, a subsequent attempt to relock the PLL will result in PLL successfully locking.
This patch does the following as per the errata recommendation:
- retries locking the PLL upto 20 times.
- The time to wait for a PLL lock set to 1000 REFCLK cycles. We use usleep_range to wait for 1000 REFCLK cycles in the us range. This tight constraint is imposed as a lock later than 1000 REFCLK cycles may have high jitter.
- Criteria for PLL lock is extended from check on just the PLL_LOCK bit to check on 6 PLL_STATUS bits.
Silicon Versions Impacted: DRA71, DRA72, DRA74, DRA76 - All silicon revisions AM57x - All silicon revisions
OMAP4/5 are not impacted by this errata
Signed-off-by: Venkateswara Rao Mandela venkat.mandela@ti.com [tomi.valkeinen@ti.com: ported to v4.14] Signed-off-by: Tomi Valkeinen tomi.valkeinen@ti.com --- drivers/gpu/drm/omapdrm/dss/dss.h | 3 + drivers/gpu/drm/omapdrm/dss/pll.c | 73 +++++++++++++++++++++---- drivers/gpu/drm/omapdrm/dss/video-pll.c | 1 + 3 files changed, 67 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/omapdrm/dss/dss.h b/drivers/gpu/drm/omapdrm/dss/dss.h index 847c78ade024..9f9a700bb6d5 100644 --- a/drivers/gpu/drm/omapdrm/dss/dss.h +++ b/drivers/gpu/drm/omapdrm/dss/dss.h @@ -180,6 +180,9 @@ struct dss_pll_hw {
/* DRA7 errata i886: use high N & M to avoid jitter */ bool errata_i886; + + /* DRA7 errata i932: retry pll lock on failure */ + bool errata_i932; };
struct dss_pll { diff --git a/drivers/gpu/drm/omapdrm/dss/pll.c b/drivers/gpu/drm/omapdrm/dss/pll.c index 078b0e8216c3..ff362b38bf0d 100644 --- a/drivers/gpu/drm/omapdrm/dss/pll.c +++ b/drivers/gpu/drm/omapdrm/dss/pll.c @@ -16,6 +16,7 @@
#define DSS_SUBSYS_NAME "PLL"
+#include <linux/delay.h> #include <linux/clk.h> #include <linux/io.h> #include <linux/kernel.h> @@ -381,6 +382,22 @@ static int dss_wait_hsdiv_ack(struct dss_pll *pll, u32 hsdiv_ack_mask) return -ETIMEDOUT; }
+static bool pll_is_locked(u32 stat) +{ + /* + * Required value for each bitfield listed below + * + * PLL_STATUS[6] = 0 PLL_BYPASS + * PLL_STATUS[5] = 0 PLL_HIGHJITTER + * + * PLL_STATUS[3] = 0 PLL_LOSSREF + * PLL_STATUS[2] = 0 PLL_RECAL + * PLL_STATUS[1] = 1 PLL_LOCK + * PLL_STATUS[0] = 1 PLL_CTRL_RESET_DONE + */ + return ((stat & 0x6f) == 0x3); +} + int dss_pll_write_config_type_a(struct dss_pll *pll, const struct dss_pll_clock_info *cinfo) { @@ -436,18 +453,54 @@ int dss_pll_write_config_type_a(struct dss_pll *pll, l = FLD_MOD(l, 0, 25, 25); /* M7_CLOCK_EN */ writel_relaxed(l, base + PLL_CONFIGURATION2);
- writel_relaxed(1, base + PLL_GO); /* PLL_GO */ + if (hw->errata_i932) { + int cnt = 0; + u32 sleep_time; + const u32 max_lock_retries = 20;
- if (wait_for_bit_change(base + PLL_GO, 0, 0) != 0) { - DSSERR("DSS DPLL GO bit not going down.\n"); - r = -EIO; - goto err; - } + /* + * Calculate wait time for PLL LOCK + * 1000 REFCLK cycles in us. + */ + sleep_time = DIV_ROUND_UP(1000*1000*1000, cinfo->fint);
- if (wait_for_bit_change(base + PLL_STATUS, 1, 1) != 1) { - DSSERR("cannot lock DSS DPLL\n"); - r = -EIO; - goto err; + for (cnt = 0; cnt < max_lock_retries; cnt++) { + writel_relaxed(1, base + PLL_GO); /* PLL_GO */ + + /** + * read the register back to ensure the write is + * flushed + */ + readl_relaxed(base + PLL_GO); + + usleep_range(sleep_time, sleep_time + 5); + l = readl_relaxed(base + PLL_STATUS); + + if (pll_is_locked(l) && + !(readl_relaxed(base + PLL_GO) & 0x1)) + break; + + } + + if (cnt == max_lock_retries) { + DSSERR("cannot lock PLL\n"); + r = -EIO; + goto err; + } + } else { + writel_relaxed(1, base + PLL_GO); /* PLL_GO */ + + if (wait_for_bit_change(base + PLL_GO, 0, 0) != 0) { + DSSERR("DSS DPLL GO bit not going down.\n"); + r = -EIO; + goto err; + } + + if (wait_for_bit_change(base + PLL_STATUS, 1, 1) != 1) { + DSSERR("cannot lock DSS DPLL\n"); + r = -EIO; + goto err; + } }
l = readl_relaxed(base + PLL_CONFIGURATION2); diff --git a/drivers/gpu/drm/omapdrm/dss/video-pll.c b/drivers/gpu/drm/omapdrm/dss/video-pll.c index 585ed94ccf17..cb46311f92c9 100644 --- a/drivers/gpu/drm/omapdrm/dss/video-pll.c +++ b/drivers/gpu/drm/omapdrm/dss/video-pll.c @@ -134,6 +134,7 @@ static const struct dss_pll_hw dss_dra7_video_pll_hw = { .has_refsel = true,
.errata_i886 = true, + .errata_i932 = true, };
struct dss_pll *dss_video_pll_init(struct dss_device *dss,