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Message-ID: <5767EACE.6030304@ti.com>
Date: Mon, 20 Jun 2016 18:38:30 +0530
From: Kishon Vijay Abraham I <kishon@...com>
To: Douglas Anderson <dianders@...omium.org>, <ulf.hansson@...aro.org>,
Heiko Stuebner <heiko@...ech.de>, <robh+dt@...nel.org>
CC: <shawn.lin@...k-chips.com>, <xzy.xu@...k-chips.com>,
<briannorris@...omium.org>, <adrian.hunter@...el.com>,
<linux-rockchip@...ts.infradead.org>, <linux-mmc@...r.kernel.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 10/11] phy: rockchip-emmc: Set phyctrl_frqsel based on
card clock
On Tuesday 14 June 2016 04:34 AM, Douglas Anderson wrote:
> The "phyctrl_frqsel" is described in the Arasan datasheet [1] as "the
> frequency range of DLL operation". Although the Rockchip variant of
> this PHY has different ranges than the reference Arasan PHY it appears
> as if the functionality is similar. We should set this phyctrl field
> properly.
>
> Note: as per Rockchip engineers, apparently the "phyctrl_frqsel" is
> actually only useful in HS200 / HS400 modes even though the DLL itself
> it used for some purposes in all modes. See the discussion in the
> earlier change in this series: ("mmc: sdhci-of-arasan: Always power the
> PHY off/on when clock changes"). In any case, it shouldn't hurt to set
> this always.
>
> Note that this change should allow boards to run at HS200 / HS400 speed
> modes while running at 100 MHz or 150 MHz. In fact, running HS400 at
> 150 MHz (giving 300 MB/s) is the main motivation of this series, since
> performance is still good but signal integrity problems are less
> prevelant at 150 MHz.
>
> [1]: https://arasan.com/wp-content/media/eMMC-5-1-Total-Solution_Rev-1-3.pdf
>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
Acked-by: Kishon Vijay Abraham I <kishon@...com>
> ---
> Changes in v2:
> - Warn if we're more than 15 MHz from ideal rate (Shawn)
> - Move code cleanup before set phyctrl_frqsel based on card clock (Shawn)
> - Fix typo USB => SDHCI (Shawn)
>
> drivers/phy/phy-rockchip-emmc.c | 82 ++++++++++++++++++++++++++++++++++-------
> 1 file changed, 69 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/phy/phy-rockchip-emmc.c b/drivers/phy/phy-rockchip-emmc.c
> index 23fe50864526..51ddd543fd04 100644
> --- a/drivers/phy/phy-rockchip-emmc.c
> +++ b/drivers/phy/phy-rockchip-emmc.c
> @@ -14,6 +14,7 @@
> * GNU General Public License for more details.
> */
>
> +#include <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/mfd/syscon.h>
> #include <linux/module.h>
> @@ -78,16 +79,73 @@
> struct rockchip_emmc_phy {
> unsigned int reg_offset;
> struct regmap *reg_base;
> + struct clk *emmcclk;
> };
>
> -static int rockchip_emmc_phy_power(struct rockchip_emmc_phy *rk_phy,
> - bool on_off)
> +static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
> {
> + struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
> unsigned int caldone;
> unsigned int dllrdy;
> + unsigned int freqsel = PHYCTRL_FREQSEL_200M;
> unsigned long timeout;
>
> /*
> + * We purposely get the clock here and not in probe to avoid the
> + * circular dependency problem. We expect:
> + * - PHY driver to probe
> + * - SDHCI driver to start probe
> + * - SDHCI driver to register it's clock
> + * - SDHCI driver to get the PHY
> + * - SDHCI driver to power on the PHY
> + */
> + if (!rk_phy->emmcclk) {
> + rk_phy->emmcclk = devm_clk_get(&phy->dev, "emmcclk");
> +
> + /* Don't expect defer at this point; try next time */
> + if (PTR_ERR(rk_phy->emmcclk) == -EPROBE_DEFER) {
> + dev_warn(&phy->dev, "Unexpected emmcclk defer\n");
> + rk_phy->emmcclk = NULL;
> + }
> + }
> +
> + if (!IS_ERR_OR_NULL(rk_phy->emmcclk)) {
> + unsigned long rate = clk_get_rate(rk_phy->emmcclk);
> + unsigned long ideal_rate;
> + unsigned long diff;
> +
> + switch (rate) {
> + case 0 ... 74999999:
> + ideal_rate = 50000000;
> + freqsel = PHYCTRL_FREQSEL_50M;
> + break;
> + case 75000000 ... 124999999:
> + ideal_rate = 100000000;
> + freqsel = PHYCTRL_FREQSEL_100M;
> + break;
> + case 125000000 ... 174999999:
> + ideal_rate = 150000000;
> + freqsel = PHYCTRL_FREQSEL_150M;
> + break;
> + default:
> + ideal_rate = 200000000;
> + break;
> + };
> +
> + diff = (rate > ideal_rate) ?
> + rate - ideal_rate : ideal_rate - rate;
> +
> + /*
> + * In order for tuning delays to be accurate we need to be
> + * pretty spot on for the DLL range, so warn if we're too
> + * far off. Also warn if we're above the 200 MHz max. Don't
> + * warn for really slow rates since we won't be tuning then.
> + */
> + if ((rate > 50000000 && diff > 15000000) || (rate > 200000000))
> + dev_warn(&phy->dev, "Unsupported rate: %lu\n", rate);
> + }
> +
> + /*
> * Keep phyctrl_pdb and phyctrl_endll low to allow
> * initialization of CALIO state M/C DFFs
> */
> @@ -132,6 +190,13 @@ static int rockchip_emmc_phy_power(struct rockchip_emmc_phy *rk_phy,
> return -ETIMEDOUT;
> }
>
> + /* Set the frequency of the DLL operation */
> + regmap_write(rk_phy->reg_base,
> + rk_phy->reg_offset + GRF_EMMCPHY_CON0,
> + HIWORD_UPDATE(freqsel, PHYCTRL_FREQSEL_MASK,
> + PHYCTRL_FREQSEL_SHIFT));
> +
> + /* Turn on the DLL */
> regmap_write(rk_phy->reg_base,
> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
> HIWORD_UPDATE(PHYCTRL_ENDLL_ENABLE,
> @@ -168,23 +233,14 @@ static int rockchip_emmc_phy_power(struct rockchip_emmc_phy *rk_phy,
>
> static int rockchip_emmc_phy_power_off(struct phy *phy)
> {
> - struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
> -
> /* Power down emmc phy analog blocks */
> - return rockchip_emmc_phy_power(rk_phy, PHYCTRL_PDB_PWR_OFF);
> + return rockchip_emmc_phy_power(phy, PHYCTRL_PDB_PWR_OFF);
> }
>
> static int rockchip_emmc_phy_power_on(struct phy *phy)
> {
> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>
> - /* DLL operation: 200 MHz */
> - regmap_write(rk_phy->reg_base,
> - rk_phy->reg_offset + GRF_EMMCPHY_CON0,
> - HIWORD_UPDATE(PHYCTRL_FREQSEL_200M,
> - PHYCTRL_FREQSEL_MASK,
> - PHYCTRL_FREQSEL_SHIFT));
> -
> /* Drive impedance: 50 Ohm */
> regmap_write(rk_phy->reg_base,
> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
> @@ -207,7 +263,7 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
> PHYCTRL_OTAPDLYSEL_SHIFT));
>
> /* Power up emmc phy analog blocks */
> - return rockchip_emmc_phy_power(rk_phy, PHYCTRL_PDB_PWR_ON);
> + return rockchip_emmc_phy_power(phy, PHYCTRL_PDB_PWR_ON);
> }
>
> static const struct phy_ops ops = {
>
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