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<6eede805-80fd-016f-22f8-b6d25f6587af@nvidia.com> <1c12e40e-de7f-0599-a941-82760b4c7668@gmail.com> From: Sowjanya Komatineni Message-ID: <9ef0b875-e826-43e2-207e-168d2081ff6a@nvidia.com> Date: Wed, 5 Aug 2020 10:04:16 -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: <1c12e40e-de7f-0599-a941-82760b4c7668@gmail.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) 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=1596647008; bh=bGvI/GDbSbcrEdWCWxP7QLtSQBp4oaiXd4t3MzJt/QI=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=ay6STMQsYeRSKnPVgCBJo4cpD8u6OFKJYwgoGYbiMkFrZWZjIrdnk9s/bU0Gu+NYp Oxyuu1wof0hJHq0E9TF06KE+cipFULN5i0lF2f5QWwRQot6vw7uGr/eFf1rm1c7MV7 mPiQ/+5mHiszObgvH1EP9yt4TFHhre9CPo1qJklyWnoy5XcN6AWlFSqPph5qCUsKqp gLcMTWhB5FlhDpriYk9u23xuI4Sg8+fAOSI0bBX3Z8oOMn/3T/hiDjIp4PFE6NnuVg n768paV0K5OLXCRffvFal9DrWEya6vwkuyCxgwooeOZulA+NKZidKLKIXjDDrLz5Yo 6NdeRDVwrUvhg== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 wrote= : >>>>>>>> With the split of MIPI calibration into tegra_mipi_calibrate() and >>>>>>>> tegra_mipi_wait(), MIPI clock is not kept enabled till the >>>>>>>> calibration >>>>>>>> is done. >>>>>>>> >>>>>>>> So, this patch skips disabling MIPI clock after triggering start o= f >>>>>>>> calibration and disables it only after waiting for done status fro= m >>>>>>>> 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 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 drivers/gpu/drm/tegra/dsi.c |=C2=A0 4 ++-- >>>>>>>> =C2=A0=C2=A0 drivers/gpu/host1x/mipi.c=C2=A0=C2=A0 | 19 +++++++++= +--------- >>>>>>>> =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 3 files changed, 15 insertions(+), 13 deletions(-) >>>>>>>> >>>>>>>> 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 DSI_= PAD_PREEMP_PD(0x03) | DSI_PAD_PREEMP_PU(0x3); >>>>>>>> =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 err =3D tegra_mipi_calibrate(dsi= ->mipi); >>>>>>>> +=C2=A0=C2=A0=C2=A0 err =3D tegra_mipi_start_calibration(dsi->mipi= ); >>>>>>>> =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 retu= rn err; >>>>>>>> =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->mipi= ); >>>>>>>> =C2=A0=C2=A0 } >>>>>>>> =C2=A0=C2=A0 =C2=A0 static void tegra_dsi_set_timeout(struct tegr= a_dsi *dsi, >>>>>>>> unsigned long bclk, >>>>>>>> diff --git a/drivers/gpu/host1x/mipi.c 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 EXPORT_SYMBOL(tegra_mipi_disable); >>>>>>>> =C2=A0=C2=A0 -int tegra_mipi_wait(struct tegra_mipi_device *devic= e) >>>>>>>> +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 MIPI_CAL_STATU= S >>>>>>> registers here? We don't clear the START bit in the former when the >>>>>>> calibration has successfully finished, but I suspect that's because >>>>>>> the bit is self-clearing. But I wonder if we still need to 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 unnecessary. >>>>>> >>>>>> Perhaps having a fixed delay before disabling clock could be enough = to >>>>>> ensure that calibration is stopped before the clock is disabled? >>>>>> >>>>> Actually, there is a MIPI_CAL_ACTIVE bit in the status register. Mayb= e >>>>> 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 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 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 enabled > What enables the UART_FST_CAL clock? I don't see this clock used 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 sequence=20 codes by the time csi stream and sensor stream happens which is where we=20 check for calibration to complete for sure calibration will be finished=20 and calibration logic will only wait for pads to be in LP-11 to apply=20 results. So nothing special needed during cancel except to turn clock=20 off to balance its usage count.