From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754678AbcK3Emh (ORCPT ); Tue, 29 Nov 2016 23:42:37 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:35166 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751952AbcK3Em1 (ORCPT ); Tue, 29 Nov 2016 23:42:27 -0500 DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org C2CBD61406 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=architt@codeaurora.org Subject: Re: [RFC][PATCH 5/5 v2] drm/bridge: adv7511: Reuse __adv7511_power_on/off() when probing EDID To: John Stultz , lkml References: <1480395884-5471-1-git-send-email-john.stultz@linaro.org> <1480395884-5471-6-git-send-email-john.stultz@linaro.org> Cc: David Airlie , Wolfram Sang , Lars-Peter Clausen , Laurent Pinchart , dri-devel@lists.freedesktop.org From: Archit Taneja Message-ID: Date: Wed, 30 Nov 2016 10:12:20 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1480395884-5471-6-git-send-email-john.stultz@linaro.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/29/2016 10:34 AM, John Stultz wrote: > I've found that by just turning the chip on and off via the > POWER_DOWN register, I end up getting i2c_transfer errors > on HiKey. > > Investigating further, it seems some of the register state > in the regmap cache is somehow getting lost. Using the logic > in __adv7511_power_on/off() which syncs and dirtys the cache > avoids this issue. > > Thus this patch changes the EDID probing logic so that we > re-use the __adv7511_power_on/off() calls. > > Cc: David Airlie > Cc: Archit Taneja > Cc: Wolfram Sang > Cc: Lars-Peter Clausen > Cc: Laurent Pinchart > Cc: dri-devel@lists.freedesktop.org > Signed-off-by: John Stultz > --- > v2: Split into two patches to make the change more clear. > Also provided more rational as to why the change is > important. > > drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 17 +++-------------- > 1 file changed, 3 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > index 1948968..487b33d 100644 > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > @@ -559,24 +559,13 @@ static int adv7511_get_modes(struct adv7511 *adv7511, > unsigned int count; > > /* Reading the EDID only works if the device is powered */ > - if (!adv7511->powered) { > - regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER, > - ADV7511_POWER_POWER_DOWN, 0); > - if (adv7511->i2c_main->irq) { > - regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(0), > - ADV7511_INT0_EDID_READY); > - regmap_write(adv7511->regmap, ADV7511_REG_INT_ENABLE(1), > - ADV7511_INT1_DDC_ERROR); > - } > - adv7511->current_edid_segment = -1; > - } > + if (!adv7511->powered) > + __adv7511_power_on(adv7511); In terms of changes in terms of register configurations, replacing with __adv7511_power_on() here would add a register write to ADV7511_REG_POWER2 as discussed before. Also, after the patch that enables HPD, we'd also be adding the ADV7511_INT0_HPD bit in ADV7511_REG_INT_ENABLE(0). I am not entirely sure about what effect adding POWER2 would have. If we don't see any negative effects because of it, I think we should be fine. The extra HPD bit in INT_ENABLE(0) shouldn't be a problem, though. In fact, it prevents the HPD mask from being cleared after we get_modes is called, which may have resulted in us missing out on HPD interrupts. Thanks, Archit > > edid = drm_do_get_edid(connector, adv7511_get_edid_block, adv7511); > > if (!adv7511->powered) > - regmap_update_bits(adv7511->regmap, ADV7511_REG_POWER, > - ADV7511_POWER_POWER_DOWN, > - ADV7511_POWER_POWER_DOWN); > + __adv7511_power_off(adv7511); > > kfree(adv7511->edid); > adv7511->edid = edid; > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project