[RFC PATCH 2/2] gpmi-nand: Add ERR007117 protection for nfc_apply_timings

Stefan Riedmueller
2021-10-12T09:03:17Z

According to i.MX 6 erratum ERR007117 gpmi clocks need to be gated off
when doing a gpmi_io clk rate change. So gate the clocks off before
the rate change in nfc_apply_timings and ungate them again after the
change.

Otherwise this rate change can lead to an unresponsive GPMI core which
results in DMA timeouts and failed driver probe:

[ 4.072318] gpmi-nand 112000.gpmi-nand: DMA timeout, last DMA
...
[ 4.370355] gpmi-nand 112000.gpmi-nand: Chip: 0, Error -110
...
[ 4.375988] gpmi-nand 112000.gpmi-nand: Chip: 0, Error -22
[ 4.381524] gpmi-nand 112000.gpmi-nand: Error in ECC-based read: -22
[ 4.387988] gpmi-nand 112000.gpmi-nand: Chip: 0, Error -22
[ 4.393535] gpmi-nand 112000.gpmi-nand: Chip: 0, Error -22
...

Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
---
Hi,

I'm not sure about the error handling here, if it is actually neccessary.
So some feedback would be nice here.

Thanks,
Stefan
---
drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
index a1f7000f033e..326c8a895f1f 100644
--- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
@@ -713,15 +713,28 @@ static void gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
(use_half_period ? BM_GPMI_CTRL1_HALF_PERIOD : 0);
}

-static void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
+static int gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
{
struct gpmi_nfc_hardware_timing *hw = &this->hw;
struct resources *r = &this->resources;
void __iomem *gpmi_regs = r->gpmi_regs;
unsigned int dll_wait_time_us;
+ int ret;
+
+ if (GPMI_IS_MX6Q(this)) {
+ ret = __gpmi_enable_clk(this, false);
+ if (ret)
+ return ret;
+ }

clk_set_rate(r->clock[0], hw->clk_rate);

+ if (GPMI_IS_MX6Q(this)) {
+ ret = __gpmi_enable_clk(this, true);
+ if (ret)
+ return ret;
+ }
+
writel(hw->timing0, gpmi_regs + HW_GPMI_TIMING0);
writel(hw->timing1, gpmi_regs + HW_GPMI_TIMING1);

@@ -739,6 +752,8 @@ static void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)

/* Wait for the DLL to settle. */
udelay(dll_wait_time_us);
+
+ return 0;
}

static int gpmi_setup_interface(struct nand_chip *chip, int chipnr,
@@ -2271,7 +2286,9 @@ static int gpmi_nfc_exec_op(struct nand_chip *chip,
*/
if (this->hw.must_apply_timings) {
this->hw.must_apply_timings = false;
- gpmi_nfc_apply_timings(this);
+ ret = gpmi_nfc_apply_timings(this);
+ if (ret)
+ return ret;
}

dev_dbg(this->dev, "%s: %d instructions\n", __func__, op->ninstrs);
--
2.25.1