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<6eede805-80fd-016f-22f8-b6d25f6587af@nvidia.com> <1c12e40e-de7f-0599-a941-82760b4c7668@gmail.com> <9ef0b875-e826-43e2-207e-168d2081ff6a@nvidia.com> Message-ID: <4689cfe9-e7c4-48bf-217f-3a31b59b8bda@nvidia.com> Date: Wed, 5 Aug 2020 10:29:16 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <9ef0b875-e826-43e2-207e-168d2081ff6a@nvidia.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1596648458; bh=QAIj5bzl4Avs4KvoHHn+vuoiKrqAhIr+EfycWcA2t5U=; h=X-PGP-Universal:Subject:From:To:CC:References:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=WDpeP0DHVknDbGWKsv2XzEZeWmOcDilmKFZVmOArKnDx6jf0fr++xlgtswsaF2oVd d1bDJSH3Ynzu2F7s15tvS466YO8g2IglD+LcyAGZ1wORw2Qq/M/NDFhQuQnRL67FVa pIY6KJrQoaMbIsD5Wnci4+iHwJ9t5jgx4u1iOrkORh19JbtI2CeOvzBPd/SL8JZV2q IoO7cdG8ymSPHyx/3ChVTcC6mBufG+kOHDa9EQxvw5jy4QoWxpacUp3wrL1e+mNwK1 BJBfY6hSh9gNTCzXoB8kYOtb558gAQbqY7KFoP4ja1WDIe3KVq+BpjVOeHlQesnoCi gxNWIohO3/OgA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/5/20 10:04 AM, Sowjanya Komatineni wrote: > > On 8/5/20 9:57 AM, Dmitry Osipenko wrote: >> 05.08.2020 19:50, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> On 8/5/20 9:47 AM, Dmitry Osipenko wrote: >>>> 05.08.2020 19:33, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>>> On 8/5/20 7:19 AM, Dmitry Osipenko wrote: >>>>>> 05.08.2020 17:05, Dmitry Osipenko =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>>>>> 05.08.2020 16:46, Thierry Reding =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>>>>>> On Mon, Aug 03, 2020 at 08:42:24AM -0700, Sowjanya Komatineni=20 >>>>>>>> wrote: >>>>>>>>> With the split of MIPI calibration into tegra_mipi_calibrate()=20 >>>>>>>>> and >>>>>>>>> tegra_mipi_wait(), MIPI clock is not kept enabled till the >>>>>>>>> calibration >>>>>>>>> is done. >>>>>>>>> >>>>>>>>> So, this patch skips disabling MIPI clock after triggering=20 >>>>>>>>> start of >>>>>>>>> calibration and disables it only after waiting for done status=20 >>>>>>>>> from >>>>>>>>> the calibration logic. >>>>>>>>> >>>>>>>>> This patch renames tegra_mipi_calibrate() as >>>>>>>>> tegra_mipi_start_calibration() >>>>>>>>> and tegra_mipi_wait() as tegra_mipi_finish_calibration() to be >>>>>>>>> inline >>>>>>>>> with their usage. >>>>>>>>> >>>>>>>>> As MIPI clock is left enabled and in case of any failures with=20 >>>>>>>>> CSI >>>>>>>>> input >>>>>>>>> streaming tegra_mipi_finish_calibration() will not get invoked. >>>>>>>>> So added new API tegra_mipi_cancel_calibration() which disables >>>>>>>>> MIPI clock >>>>>>>>> and consumer drivers can call this in such cases. >>>>>>>>> >>>>>>>>> Reviewed-by: Dmitry Osipenko >>>>>>>>> Signed-off-by: Sowjanya Komatineni >>>>>>>>> --- >>>>>>>>> =C2=A0=C2=A0=C2=A0 drivers/gpu/drm/tegra/dsi.c |=C2=A0 4 ++-- >>>>>>>>> =C2=A0=C2=A0=C2=A0 drivers/gpu/host1x/mipi.c=C2=A0=C2=A0 | 19 +++= +++++++--------- >>>>>>>>> =C2=A0=C2=A0=C2=A0 include/linux/host1x.h=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 |=C2=A0 5 +++-- >>>>>>>>> =C2=A0=C2=A0=C2=A0 3 files changed, 15 insertions(+), 13 deletion= s(-) >>>>>>>>> >>>>>>>>> diff --git a/drivers/gpu/drm/tegra/dsi.c >>>>>>>>> b/drivers/gpu/drm/tegra/dsi.c >>>>>>>>> index 3820e8d..a7864e9 100644 >>>>>>>>> --- a/drivers/gpu/drm/tegra/dsi.c >>>>>>>>> +++ b/drivers/gpu/drm/tegra/dsi.c >>>>>>>>> @@ -694,11 +694,11 @@ static int tegra_dsi_pad_calibrate(struct >>>>>>>>> tegra_dsi *dsi) >>>>>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 DSI_PAD_PREEMP_PD(0x03) | DSI_PAD_PREEMP_PU(0x3); >>>>>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 tegra_dsi_writel(dsi, = value, DSI_PAD_CONTROL_3); >>>>>>>>> =C2=A0=C2=A0=C2=A0 -=C2=A0=C2=A0=C2=A0 err =3D tegra_mipi_calibra= te(dsi->mipi); >>>>>>>>> +=C2=A0=C2=A0=C2=A0 err =3D tegra_mipi_start_calibration(dsi->mip= i); >>>>>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (err < 0) >>>>>>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 return err; >>>>>>>>> =C2=A0=C2=A0=C2=A0 -=C2=A0=C2=A0=C2=A0 return tegra_mipi_wait(dsi= ->mipi); >>>>>>>>> +=C2=A0=C2=A0=C2=A0 return tegra_mipi_finish_calibration(dsi->mip= i); >>>>>>>>> =C2=A0=C2=A0=C2=A0 } >>>>>>>>> =C2=A0=C2=A0=C2=A0 =C2=A0 static void tegra_dsi_set_timeout(struc= t tegra_dsi *dsi, >>>>>>>>> unsigned long bclk, >>>>>>>>> diff --git a/drivers/gpu/host1x/mipi.c=20 >>>>>>>>> b/drivers/gpu/host1x/mipi.c >>>>>>>>> index e606464..b15ab6e 100644 >>>>>>>>> --- a/drivers/gpu/host1x/mipi.c >>>>>>>>> +++ b/drivers/gpu/host1x/mipi.c >>>>>>>>> @@ -293,17 +293,19 @@ int tegra_mipi_disable(struct >>>>>>>>> tegra_mipi_device *dev) >>>>>>>>> =C2=A0=C2=A0=C2=A0 } >>>>>>>>> =C2=A0=C2=A0=C2=A0 EXPORT_SYMBOL(tegra_mipi_disable); >>>>>>>>> =C2=A0=C2=A0=C2=A0 -int tegra_mipi_wait(struct tegra_mipi_device = *device) >>>>>>>>> +void tegra_mipi_cancel_calibration(struct tegra_mipi_device >>>>>>>>> *device) >>>>>>>>> +{ >>>>>>>>> +=C2=A0=C2=A0=C2=A0 clk_disable(device->mipi->clk); >>>>>>>> Do we need to do anything with the MIPI_CAL_CTRL and=20 >>>>>>>> MIPI_CAL_STATUS >>>>>>>> registers here? We don't clear the START bit in the former when=20 >>>>>>>> the >>>>>>>> calibration has successfully finished, but I suspect that's=20 >>>>>>>> because >>>>>>>> the bit is self-clearing. But I wonder if we still need to=20 >>>>>>>> clear it >>>>>>>> upon cancellation to make sure the calibration does indeed stop. >>>>>>> Apparently there is no way to explicitly stop calibration other >>>>>>> than to >>>>>>> reset MIPI calibration block, but Sowjanya says this is=20 >>>>>>> unnecessary. >>>>>>> >>>>>>> Perhaps having a fixed delay before disabling clock could be=20 >>>>>>> enough to >>>>>>> ensure that calibration is stopped before the clock is disabled? >>>>>>> >>>>>> Actually, there is a MIPI_CAL_ACTIVE bit in the status register.=20 >>>>>> Maybe >>>>>> it needs to be polled until it's unset? >>>>> Confirmed with HW design team during this patch update. >>>>> >>>>> SW does not need to clear START bit and only write 1 takes effect to >>>>> that bit. >>>>> >>>>> Also, no need to have delay or do any other register settings=20 >>>>> unclear as >>>>> its FSM and there's nothing to get stuck. >>>>> >>>>> Also it goes thru small finite set of codes and by the time sensor >>>>> programming happens for enabling streaming FSM will finish its >>>>> calibration sequence much early and it will only wait for pads LP-11. >>>>> >>>>> So, during cancel we only need disable MIPI clock. >>>>> >>>> But there is no guarantee that cancel_calibration() couldn't be=20 >>>> invoked >>>> in the middle of the calibration process, hence FSM could freeze in an >>>> intermediate state if it's running on the disabled MIPI clock, this >>>> doesn't sound good. >>> Actual calibration logic uses UART_FST_CAL clock which is always=20 >>> enabled >> What enables the UART_FST_CAL clock? I don't see this clock used=20 >> anywhere. > > UART_FST_MIPI_CAL is shared with uart and is always enabled all the time. > > I don't see mipi driver handling this and I think that's because this=20 > clock is enabled all the time as its used for UART as well. Probably=20 > thierry can comment on this clock. > > Also regarding cancel calibration, as FSM goes thru only finite=20 > sequence codes by the time csi stream and sensor stream happens which=20 > is where we check for calibration to complete for sure calibration=20 > will be finished and calibration logic will only wait for pads to be=20 > in LP-11 to apply results. So nothing special needed during cancel=20 > except to turn clock off to balance its usage count. > > UART_FST_MIPI_CAL is the clock used for calibration logic which is FSM=20 that goes thru sequence codes and when done waits for pads to be in=20 LP-11 to apply results. MIPI_CLK is controller gate clock which is also need to be kept enabled=20 as incase if it sees LP-11 it updates registers so its recommended to=20 have this clock enabled. We can cancel_calibration() in CSI only when csi/sensor stream on fails=20 and in which case there will be no LP-11 so we can unconditionally=20 disable MIPI_CLK.