Re: GPMI iMX6ull timeout on DMA

From: Michael Nazzareno Trimarchi <michael@amarulasolutions.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: linux-mtd@lists.infradead.org,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Greg Ungerer <gerg@kernel.org>,
	Boris Brezillon <bbrezillon@kernel.org>,
	Boris Brezillon <boris.brezillon@collabora.com>
Subject: Re: GPMI iMX6ull timeout on DMA
Date: Mon, 1 Feb 2021 15:32:04 +0100	[thread overview]
Message-ID: <CAOf5uwkivHhMX_mPJymBZxQge_wc4K1p_1S3gsQYHPV40aaj3w@mail.gmail.com> (raw)
In-Reply-To: <20210201151335.210af8ca@xps13>

Hi

On Mon, Feb 1, 2021 at 3:13 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>
> Hi Michael,
>
> Michael Nazzareno Trimarchi <michael@amarulasolutions.com> wrote on
> Sat, 30 Jan 2021 10:41:29 +0100:
>
> > Hi Miquel
> >
> > commit f8e6ad14388067f91b26d044185d95623fbc9535
> > Author: Michael Trimarchi <michael@amarulasolutions.com>
> > Date:   Fri Jan 29 08:46:53 2021 +0100
> >
> >     mtd: nand: Calculate the clock before enable it
> >
> >     Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
> >     Change-Id: I79b0da39de0a9b32ea0b002fa200d7f44d4f8ce7
> >
> > diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > b/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > index 322a008290e5..0bca52b3bc8f 100644
> > --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > @@ -377,6 +377,7 @@ static void gpmi_nfc_compute_timings(struct
> > gpmi_nand_data *this,
> >                                      const struct nand_sdr_timings *sdr)
> >  {
> >         struct gpmi_nfc_hardware_timing *hw = &this->hw;
> > +       struct resources *r = &this->resources;
> >         unsigned int dll_threshold_ps = this->devdata->max_chain_delay;
> >         unsigned int period_ps, reference_period_ps;
> >         unsigned int data_setup_cycles, data_hold_cycles, addr_setup_cycles;
> > @@ -440,6 +441,8 @@ static void gpmi_nfc_compute_timings(struct
> > gpmi_nand_data *this,
> >                 hw->ctrl1n |= BF_GPMI_CTRL1_RDN_DELAY(sample_delay_factor) |
> >                               BM_GPMI_CTRL1_DLL_ENABLE |
> >                               (use_half_period ? BM_GPMI_CTRL1_HALF_PERIOD : 0);
> > +
> > +       clk_set_rate(r->clock[0], hw->clk_rate);
> >  }
> >
> >  void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
> > @@ -449,8 +452,6 @@ void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
> >         void __iomem *gpmi_regs = r->gpmi_regs;
> >         unsigned int dll_wait_time_us;
> >
> > -       clk_set_rate(r->clock[0], hw->clk_rate);
> > -
> >         writel(hw->timing0, gpmi_regs + HW_GPMI_TIMING0);
> >         writel(hw->timing1, gpmi_regs + HW_GPMI_TIMING1);
> >
> > Right now I have this change applied and seems fine. That is the only
> > difference I get. Clock is apply a bit earlier that when is enabled
> > it.
>
> This is very interesting. So this would mean the issue you are
> experiencing comes from the clock driver which kind of returns too
> early from clk_set_rate()? Could you report this to the clk ML/NXP clk
> maintainers and keep us in copy? If it is as global as it sounds, we
> might not be the only ones affected.
>

The imx28 is broken too, so it's a general problem. I need to trace it down
I have a reverting for lts but it\s not the way to go

Michael

> Thanks,
> Miquèl

-- 
Michael Nazzareno Trimarchi
Amarula Solutions BV
COO Co-Founder
Cruquiuskade 47 Amsterdam 1018 AM NL
T. +31(0)851119172
M. +39(0)3479132170
[`as] https://www.amarulasolutions.com

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