linux-kernel - Re: [PATCH] drm/rockchip: vop: do axi reset in vop initial time

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Date:	Thu, 2 Jun 2016 11:11:41 +0800
From:	Yakir Yang <ykk@...k-chips.com>
To:	Thierry Reding <treding@...dia.com>
Cc:	Mark Yao <yzq@...k-chips.com>, Heiko Stuebner <heiko@...ech.de>,
	tfiga@...omium.org, David Airlie <airlied@...ux.ie>,
	daniel.vetter@...ll.ch, dianders@...omium.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH] drm/rockchip: vop: do axi reset in vop initial time


On 06/01/2016 11:19 PM, Thierry Reding wrote:
> On Wed, Jun 01, 2016 at 05:19:12PM +0800, Yakir Yang wrote:
>> There is a bug in RK3399 VOP, when bootloader/kernel only enable
>> VOP Big or VOP Little to display, then VOP IOMMU would failed to
>> reset at the initial time and VOP register couldn't write rightly.
>>
>> After do the pure reset of VOP module, then things back to right.
>>
>> Signed-off-by: Yakir Yang <ykk@...k-chips.com>
>> ---
>>   drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 15 ++++++++++++++-
>>   1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>> index 1c4d5b5..4150323 100644
>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>> @@ -1292,7 +1292,7 @@ static int vop_initial(struct vop *vop)
>>   {
>>   	const struct vop_data *vop_data = vop->data;
>>   	const struct vop_reg_data *init_table = vop_data->init_table;
>> -	struct reset_control *ahb_rst;
>> +	struct reset_control *ahb_rst, *axi_rst;
>>   	int i, ret;
>>   
>>   	vop->hclk = devm_clk_get(vop->dev, "hclk_vop");
>> @@ -1331,6 +1331,19 @@ static int vop_initial(struct vop *vop)
>>   	}
>>   
>>   	/*
>> +	 * do aclk_reset, reset all vop registers.
>> +	 */
>> +	axi_rst = devm_reset_control_get(vop->dev, "axi");
> I don't think you want the managed version here since you only store
> this in a local variable and hence aren't going to need it afterwards.
> Just use reset_control_get() and ...

Great, but seems Mark would not accept this fix now :(
Maybe I should found the root cause why my bootloader/kernel would 
broken the VOP.

Thanks,
- Yakir
>> +	if (IS_ERR(axi_rst)) {
>> +		dev_err(vop->dev, "failed to get axi reset\n");
>> +		ret = PTR_ERR(axi_rst);
>> +		goto err_disable_aclk;
>> +	}
>> +	reset_control_assert(axi_rst);
>> +	usleep_range(10, 20);
>> +	reset_control_deassert(axi_rst);
> call reset_control_put() here.
>
>> +
>> +	/*
>>   	 * do hclk_reset, reset all vop registers.
>>   	 */
>>   	ahb_rst = devm_reset_control_get(vop->dev, "ahb");
> This uses the same pattern, so you might want to consider reworking this
> as well, though it should be a separate patch.
>
> Thierry