From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751218AbdAPQC6 (ORCPT ); Mon, 16 Jan 2017 11:02:58 -0500 Received: from galahad.ideasonboard.com ([185.26.127.97]:51167 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750945AbdAPQC5 (ORCPT ); Mon, 16 Jan 2017 11:02:57 -0500 From: Laurent Pinchart To: dri-devel@lists.freedesktop.org Cc: John Stultz , lkml , Wolfram Sang Subject: Re: [PATCH 5/5 v3] drm/bridge: adv7511: Reuse __adv7511_power_on/off() when probing EDID Date: Mon, 16 Jan 2017 18:03:11 +0200 Message-ID: <1965576.h4kdXt2VDW@avalon> User-Agent: KMail/4.14.10 (Linux/4.8.6-gentoo; KDE/4.14.24; x86_64; ; ) In-Reply-To: <1483472502-16403-6-git-send-email-john.stultz@linaro.org> References: <1483472502-16403-1-git-send-email-john.stultz@linaro.org> <1483472502-16403-6-git-send-email-john.stultz@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi John, Thank you for the patch. On Tuesday 03 Jan 2017 11:41:42 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. regcache_sync() is quite costly as it will write a bunch of registers. Wouldn't it be more efficient to only write the registers that are needed for EDID access ? > 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 > --- > 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 dbdb71c..24573e0 > 100644 > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c > @@ -572,24 +572,13 @@ 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); > > 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; -- Regards, Laurent Pinchart