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From: Sowjanya Komatineni Message-ID: <50aa439e-a572-ce77-9d06-e060304b9bd4@nvidia.com> Date: Thu, 6 Aug 2020 11:44:04 -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: 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=1596739342; bh=hjtCqBLT9+XaCFVA4DWtudBFoaTKIKtpNhkT5ZGd7rA=; 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=ANeuKtW0WzWf1saO5fqSgMQAmjZn3w6C/Hl1i/smgxHVcxNwWmlBtXNSLhrvi3kxN C+Cl4g8TUY1dKinTCP+pEF6+4j891st7uTl3I8psuUITeLxafc/r2R8gIWS8gqCmcj jVgBROi9dq79L1oTPbbM7DmQ6sriLVZrOZQTzuBJnkwwHCiKjpytqtFNqv+x/UNaAt ZOfheuvDq3pU8GEUsnZLVAO3qxasnhv5SnWguhGYthqZqOYgXYQAGus+c7JNIYbwlP uqRsxmcM7+5Y5lG4+OlOTyzua4MUFVLmSlyuihw1Nb9t76DxtSBz8+BcUMsO/oHb5W 0xam/NpL+5otw== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/6/20 11:18 AM, Dmitry Osipenko wrote: > 06.08.2020 21:07, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> On 8/6/20 11:01 AM, Dmitry Osipenko wrote: >>> 06.08.2020 20:52, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>> ... >>>> Right mutex_unlock should happen at end of finish_calibration. >>>> >>>> With keeping mutex locked in start, we dont have to check for active t= o >>>> be 0 to issue start as mutex will keep it locked and other pads >>>> calibration can only go thru when current one is done. >>>> >>>> So instead of below sequence, its simpler to do this way? >>>> >>>> start_calibration() >>>> >>>> - mutex_lock >>>> >>>> - wait for 72uS after start >>>> >>>> finish_calibration() >>>> >>>> - keep check for ACTIVE =3D 0 and DONE =3D 1 >>> I think only the DONE bits which correspond to the mipi_device->pads >>> bitmask should be awaited. >> As next START can't be triggered when auto cal is ACTIVE, we should keep >> this in finish. >> >> As we do mutex_unlock only at end of finish, other pads calibrations >> dont go thru till the one in process is finished. >> >> So in this case ACTIVE applies to current selected pads that are under >> calibration. > Should be better to check only the relevant bits in order to catch bugs, > otherwise you may get a DONE status from the irrelevant pads. tegra_mipi_device is separate for DSI and CSI channels. mutex lock used=20 during calibrate is device specific lock. So, it will not prevent other devices to hold till on going calibration=20 is done unless we add wait for active bit before triggering start. Currently we wait for active bit at end during calibration done check=20 after start trigger. But when other devices go thru calibration in=20 parallel as lock is device specific and not common lock for all devices=20 it will trigger start but MIPI calibration logic ignore if previous=20 calibration is still in progress. Need to serialize calibration start requests from different devices=20 based on ACTIVE bit. >>> Perhaps the start_calibration() also needs to be changed to not touch >>> the MIPI_CAL_CONFIG bits of the unrelated pads? >> Driver already takes care of programming corresponding pads config only. > It writes 0 to the config of the unrelated pads, which probably isn't > nice if some pads use periodic auto-calibration. > > https://elixir.bootlin.com/linux/v5.8/source/drivers/gpu/host1x/mipi.c#L3= 50 > > Although looks like auto-calibration isn't supported by the current drive= r. Yes we don't use auto-calibration. Only common bit here is MIPI_CAL_CTRL start. All others are pad specific=20 currently.