Hi Nelson: > -----Original Message----- > From: linux-ide-owner@xxxxxxxxxxxxxxx [mailto:linux-ide-owner@xxxxxxxxxxxxxxx] > On Behalf Of Eric Nelson > Sent: Tuesday, November 19, 2013 6:12 AM > To: Marek Vasut > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; Zhu Richard-R65037; Tejun Heo; Shawn > Guo; Linux-IDE > Subject: Re: [PATCH 1/5] ahci: imx: Pull out the clock enable/disable calls > > Hi Marek, > > On 11/18/2013 01:23 PM, Marek Vasut wrote: > > Hi Eric, > > > >> Hi Marek, > >> > >> On 11/16/2013 06:20 PM, Marek Vasut wrote: > >>> The same code for enabling and disabling SATA clock was found in > >>> multiple places in the driver. Implement functions that > >>> enable/disable the SATA clock and use them in such places instead of > duplicating the code. > >>> > >>> Signed-off-by: Marek Vasut <marex@xxxxxxx> > >>> Cc: Shawn Guo <shawn.guo@xxxxxxxxxx> > >>> Cc: Richard Zhu <r65037@xxxxxxxxxxxxx> > >>> Cc: Tejun Heo <tj@xxxxxxxxxx> > >>> Cc: Linux-IDE <linux-ide@xxxxxxxxxxxxxxx> > >>> --- > >>> > >>> drivers/ata/ahci_imx.c | 133 > >>> ++++++++++++++++++++++++++++--------------------- 1 file changed, 75 > >>> insertions(+), 58 deletions(-) > >>> > >>> diff --git a/drivers/ata/ahci_imx.c b/drivers/ata/ahci_imx.c index > >>> ae2d73f..c7ee505 100644 > >>> --- a/drivers/ata/ahci_imx.c > >>> +++ b/drivers/ata/ahci_imx.c > >>> @@ -47,6 +47,73 @@ static int ahci_imx_hotplug; > >>> > >>> module_param_named(hotplug, ahci_imx_hotplug, int, 0644); > >>> MODULE_PARM_DESC(hotplug, "AHCI IMX hot-plug support (0=Don't support, > >>> 1=support)"); > >>> > >>> <snip> > >> > >> I haven't traced through all of this, but if you're copying from the > >> Freescale 3.0.35 kernel, note that there's a bug in it, and the > >> 0x7FFFFFFD really wanted to be an 0x7FFFFFFF. > > > > I'm not taking this from FSL 3.0.35, no, but thanks for pointing this out! > > > >> The way I read this comment, the writes need to happen in two > >> steps: > >> - write everything with the PHY disabled > >> - enable the PHY > >> > >> We had reports of stalls waiting for SATA drives to be enumerated > >> that were solved with this commit... > >> > >> https://github.com/boundarydevices/linux- > > imx6/commit/0186ea224ce6bd1cb4757 > >> a0f83b0090e26a021f4 > > > > [...] > > > >>> + regmap_update_bits(imxpriv->gpr, IOMUXC_GPR13, > >>> + IMX6Q_GPR13_SATA_MPLL_CLK_EN, > >>> + IMX6Q_GPR13_SATA_MPLL_CLK_EN); > > > > Isn't this snippet doing exactly what your patch does ? > > > This part is doing the "set the bit" part: > https://github.com/boundarydevices/linux-imx6/blob/boundary- > imx_3.0.35_4.1.0/arch/arm/mach-mx6/board-mx6_nitrogen6x.c#L728 > > The previous block isn't clearing the enable bit though: > > + regmap_update_bits(imxpriv->gpr, IOMUXC_GPR13, > + IMX6Q_GPR13_SATA_RX_EQ_VAL_MASK > + | IMX6Q_GPR13_SATA_RX_LOS_LVL_MASK > + | IMX6Q_GPR13_SATA_RX_DPLL_MODE_MASK > + | IMX6Q_GPR13_SATA_SPD_MODE_MASK > + | IMX6Q_GPR13_SATA_MPLL_SS_EN > + | IMX6Q_GPR13_SATA_TX_ATTEN_MASK > + | IMX6Q_GPR13_SATA_TX_BOOST_MASK > + | IMX6Q_GPR13_SATA_TX_LVL_MASK > + | IMX6Q_GPR13_SATA_TX_EDGE_RATE > + , IMX6Q_GPR13_SATA_RX_EQ_VAL_3_0_DB > + | IMX6Q_GPR13_SATA_RX_LOS_LVL_SATA2M > + | IMX6Q_GPR13_SATA_RX_DPLL_MODE_2P_4F > + | IMX6Q_GPR13_SATA_SPD_MODE_3P0G > + | IMX6Q_GPR13_SATA_MPLL_SS_EN > + | IMX6Q_GPR13_SATA_TX_ATTEN_9_16 > + | IMX6Q_GPR13_SATA_TX_BOOST_3_33_DB > + | IMX6Q_GPR13_SATA_TX_LVL_1_025_V); > > The explicit clearing of bit 1 is what was necessary (and I think it's what > the original author was after). > > This was a hard one to find, because it seems that it only shows up on some > boards, and most of the time on those boards. > > Here are some references: > http://boundarydevices.com/freescale-ubuntu-image-with-4-0-0- > kernel/#comment-60464 > http://boundarydevices.com/debian-installer-on-i-mx6-boards/#comment- > 76203 > > The symptom is (was) that U-Boot worked 100% of the time, but the kernel > failed to find the drive. > > Using 'mm' in U-Boot to clear the bit before kernel launch also allowed things > to function. > [Richard] Agree to explicit clearing of bit1, refer to the chapter "Power-Up Sequences" of "Serial Advanced Technology Attachment PHY (SATA PHY)" in iMX6 RM doc. > Regards, > > > Eric > -- > To unsubscribe from this list: send the line "unsubscribe linux-ide" in the > body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html Best Regards Richard Zhu ��.n��������+%������w��{.n�����{��'^�)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
