From 12f6153d4555450bdb93d115bdbf28bbd92ea426 Mon Sep 17 00:00:00 2001 From: Akinobu Mita Date: Mon, 11 Mar 2019 11:36:03 -0400 Subject: [PATCH] media: ov7670: don't access registers when the device is powered off Since commit 3d6a8fe25605 ("media: ov7670: hook s_power onto v4l2 core"), the device is actually powered off while the video stream is stopped. So now set_format and s_frame_interval could be called while the device is powered off, but these callbacks try to change the register settings at this time. The frame format and framerate will be restored right after power-up, so we can just postpone applying these changes at these callbacks if the device is not powered up. Fixes: 3d6a8fe25605 ("media: ov7670: hook s_power onto v4l2 core") Cc: Jonathan Corbet Signed-off-by: Akinobu Mita Reviewed-by: Lubomir Rintel Tested-by: Lubomir Rintel Signed-off-by: Sakari Ailus Signed-off-by: Mauro Carvalho Chehab --- drivers/media/i2c/ov7670.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c index e65693c..44c3eed 100644 --- a/drivers/media/i2c/ov7670.c +++ b/drivers/media/i2c/ov7670.c @@ -864,7 +864,15 @@ static int ov7675_set_framerate(struct v4l2_subdev *sd, /* Recalculate frame rate */ ov7675_get_framerate(sd, tpf); - return ov7675_apply_framerate(sd); + /* + * If the device is not powered up by the host driver do + * not apply any changes to H/W at this time. Instead + * the framerate will be restored right after power-up. + */ + if (info->on) + return ov7675_apply_framerate(sd); + + return 0; } static void ov7670_get_framerate_legacy(struct v4l2_subdev *sd, @@ -895,7 +903,16 @@ static int ov7670_set_framerate_legacy(struct v4l2_subdev *sd, info->clkrc = (info->clkrc & 0x80) | div; tpf->numerator = 1; tpf->denominator = info->clock_speed / div; - return ov7670_write(sd, REG_CLKRC, info->clkrc); + + /* + * If the device is not powered up by the host driver do + * not apply any changes to H/W at this time. Instead + * the framerate will be restored right after power-up. + */ + if (info->on) + return ov7670_write(sd, REG_CLKRC, info->clkrc); + + return 0; } /* @@ -1105,9 +1122,13 @@ static int ov7670_set_fmt(struct v4l2_subdev *sd, if (ret) return ret; - ret = ov7670_apply_fmt(sd); - if (ret) - return ret; + /* + * If the device is not powered up by the host driver do + * not apply any changes to H/W at this time. Instead + * the frame format will be restored right after power-up. + */ + if (info->on) + return ov7670_apply_fmt(sd); return 0; } -- 2.7.4