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Date: Tue, 19 Jun 2018 13:28:11 +0200
From: Boris Brezillon <boris.brezillon@...tlin.com>
To: Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc: linux-mtd@...ts.infradead.org, Rob Herring <robh+dt@...nel.org>,
linux-kbuild@...r.kernel.org, Richard Weinberger <richard@....at>,
"linux-stable #4 . 14+" <stable@...r.kernel.org>,
devicetree@...r.kernel.org,
Miquel Raynal <miquel.raynal@...tlin.com>,
linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
Brian Norris <computersforpeace@...il.com>,
David Woodhouse <dwmw2@...radead.org>,
Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v3 1/3] mtd: rawnand: denali_dt: add more clocks based
on IP datasheet
Hi Masahiro,
On Fri, 15 Jun 2018 10:18:50 +0900
Masahiro Yamada <yamada.masahiro@...ionext.com> wrote:
> According to the Denali User's Guide, this IP needs three clocks:
>
> - clk: controller core clock
>
> - clk_x: bus interface clock
>
> - ecc_clk: clock at which ECC circuitry is run
>
> Currently, denali_dt.c requires a single anonymous clock and its
> frequency. However, the driver needs to get the frequency of "clk_x"
> not "clk". This is confusing because people tend to assume the
> anonymous clock means the core clock. In fact, I got a report of
> SOCFPGA breakage because the timing parameters are calculated based
> on a wrong frequency.
>
> Instead of the cheesy implementation, the clocks in the real hardware
> should be represented in the driver and the DT-binding.
>
> However, adding new clocks would break the existing platforms. For the
> backward compatibility, the driver still accepts a single clock just as
> before. If clk_x is missing, clk_x_rate is set to a hardcoded value.
> This is fine for existing DT of Socionext UniPhier, and also fixes the
> issue of Altera (Intel) SOCFPGA because both platforms use 200 MHz for
> the bus interface clock.
>
> Fixes: 1bb88666775e ("mtd: nand: denali: handle timing parameters by setup_data_interface()")
Sorry for changing my mind, but I think this patch is doing more than
just fixing a bug. The bugfix should IMO be limited to unconditionally
setting ->clk_x_rate to 200000000 since this is what was done before
commit 1bb88666775e. And the remaining changes should go in nand/next.
Regards,
Boris
> Cc: linux-stable <stable@...r.kernel.org> #4.14+
> Reported-by: Richard Weinberger <richard@....at>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
>
> Changes in v3:
> - Change the patch order so that the bug-fix one comes the first
>
> Changes in v2:
> - Split patches into sensible chunks
>
> .../devicetree/bindings/mtd/denali-nand.txt | 5 +++
> drivers/mtd/nand/raw/denali_dt.c | 49 ++++++++++++++++++++--
> 2 files changed, 50 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/denali-nand.txt b/Documentation/devicetree/bindings/mtd/denali-nand.txt
> index 0ee8edb..f33da87 100644
> --- a/Documentation/devicetree/bindings/mtd/denali-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/denali-nand.txt
> @@ -8,6 +8,9 @@ Required properties:
> - reg : should contain registers location and length for data and reg.
> - reg-names: Should contain the reg names "nand_data" and "denali_reg"
> - interrupts : The interrupt number.
> + - clocks: should contain phandle of the controller core clock, the bus
> + interface clock, and the ECC circuit clock.
> + - clock-names: should contain "nand", "nand_x", "ecc"
>
> Optional properties:
> - nand-ecc-step-size: see nand.txt for details. If present, the value must be
> @@ -31,5 +34,7 @@ nand: nand@...00000 {
> compatible = "altr,socfpga-denali-nand";
> reg = <0xff900000 0x20>, <0xffb80000 0x1000>;
> reg-names = "nand_data", "denali_reg";
> + clocks = <&nand_clk>, <&nand_x_clk>, <&nand_ecc_clk>;
> + clock-names = "nand", "nand_x", "ecc";
> interrupts = <0 144 4>;
> };
> diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
> index cfd33e6..ce6239d 100644
> --- a/drivers/mtd/nand/raw/denali_dt.c
> +++ b/drivers/mtd/nand/raw/denali_dt.c
> @@ -27,7 +27,9 @@
>
> struct denali_dt {
> struct denali_nand_info denali;
> - struct clk *clk;
> + struct clk *clk; /* core clock */
> + struct clk *clk_x; /* bus interface clock */
> + struct clk *clk_ecc; /* ECC circuit clock */
> };
>
> struct denali_dt_data {
> @@ -114,24 +116,61 @@ static int denali_dt_probe(struct platform_device *pdev)
> if (IS_ERR(denali->host))
> return PTR_ERR(denali->host);
>
> - dt->clk = devm_clk_get(&pdev->dev, NULL);
> + /*
> + * A single anonymous clock is supported for the backward compatibility.
> + * New platforms should support all the named clocks.
> + */
> + dt->clk = devm_clk_get(&pdev->dev, "nand");
> + if (IS_ERR(dt->clk))
> + dt->clk = devm_clk_get(&pdev->dev, NULL);
> if (IS_ERR(dt->clk)) {
> dev_err(&pdev->dev, "no clk available\n");
> return PTR_ERR(dt->clk);
> }
> +
> + dt->clk_x = devm_clk_get(&pdev->dev, "nand_x");
> + if (IS_ERR(dt->clk_x))
> + dt->clk_x = NULL;
> +
> + dt->clk_ecc = devm_clk_get(&pdev->dev, "ecc");
> + if (IS_ERR(dt->clk_ecc))
> + dt->clk_ecc = NULL;
> +
> ret = clk_prepare_enable(dt->clk);
> if (ret)
> return ret;
>
> - denali->clk_x_rate = clk_get_rate(dt->clk);
> + ret = clk_prepare_enable(dt->clk_x);
> + if (ret)
> + goto out_disable_clk;
> +
> + ret = clk_prepare_enable(dt->clk_ecc);
> + if (ret)
> + goto out_disable_clk_x;
> +
> + if (dt->clk_x) {
> + denali->clk_x_rate = clk_get_rate(dt->clk_x);
> + } else {
> + /*
> + * Hardcode the clock rates for the backward compatibility.
> + * This works for both SOCFPGA and UniPhier.
> + */
> + dev_notice(&pdev->dev,
> + "necessary clock is missing. default clock rates are used.\n");
> + denali->clk_x_rate = 200000000;
> + }
>
> ret = denali_init(denali);
> if (ret)
> - goto out_disable_clk;
> + goto out_disable_clk_ecc;
>
> platform_set_drvdata(pdev, dt);
> return 0;
>
> +out_disable_clk_ecc:
> + clk_disable_unprepare(dt->clk_ecc);
> +out_disable_clk_x:
> + clk_disable_unprepare(dt->clk_x);
> out_disable_clk:
> clk_disable_unprepare(dt->clk);
>
> @@ -143,6 +182,8 @@ static int denali_dt_remove(struct platform_device *pdev)
> struct denali_dt *dt = platform_get_drvdata(pdev);
>
> denali_remove(&dt->denali);
> + clk_disable_unprepare(dt->clk_ecc);
> + clk_disable_unprepare(dt->clk_x);
> clk_disable_unprepare(dt->clk);
>
> return 0;
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