linux-kernel - Re: [PATCH 6/8] phy: allwinner: phy-sun6i-mipi-dphy: Set enable bit last

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Message-ID: <b3a2dc61-7384-17f7-2f4f-4b6bb86bcced@sholland.org>
Date:   Fri, 12 Aug 2022 17:31:54 -0500
From:   Samuel Holland <samuel@...lland.org>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Maxime Ripard <mripard@...nel.org>,
        Jagan Teki <jagan@...rulasolutions.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Maxime Ripard <maxime@...no.tech>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-phy@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH 6/8] phy: allwinner: phy-sun6i-mipi-dphy: Set enable bit
 last

Hi Paul,

On 8/12/22 7:03 AM, Paul Kocialkowski wrote:
> On Fri 12 Aug 22, 02:56, Samuel Holland wrote:
>> The A100 variant of the DPHY requires configuring the analog registers
>> before setting the global enable bit. Since this order also works on the
>> other variants, always use it, to minimize the differences between them.
> 
> Did you get a chance to actually test this with either DSI/CSI-2 hardware?

I have tested DSI output with the Clockwork DevTerm (D1 SoC) and Pine64
PinePhone (A64 SoC). I do not have any MIPI CSI hardware to test with.

> I vaguely remember that the order mattered. Do you have an idea of what the
> Allwinner BSP does too?

The Allwinner BSP makes the same change as this commit in its "lowlevel_v2x"
copy of the code, which is used for R40 and T7 (original DPHY) and A100 and D1
(updated DPHY). It does not make the change in "lowlevel_sun50iw1" (A64 SoC,
original DPHY), but I tested A64 with this change, and it works fine.

> Otherwise I could give it a try, at least with my MIPI CSI-2 setup
> that uses the driver.

This commit only changes sun6i_dphy_tx_power_on(). The code for RX is unchanged
-- in fact, it already sets SUN6I_DPHY_GCTL_REG last.

Regards,
Samuel

>> Signed-off-by: Samuel Holland <samuel@...lland.org>
>> ---
>>
>>  drivers/phy/allwinner/phy-sun6i-mipi-dphy.c | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c b/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c
>> index 625c6e1e9990..9698d68d0db7 100644
>> --- a/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c
>> +++ b/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c
>> @@ -183,10 +183,6 @@ static int sun6i_dphy_tx_power_on(struct sun6i_dphy *dphy)
>>  		     SUN6I_DPHY_TX_TIME4_HS_TX_ANA0(3) |
>>  		     SUN6I_DPHY_TX_TIME4_HS_TX_ANA1(3));
>>  
>> -	regmap_write(dphy->regs, SUN6I_DPHY_GCTL_REG,
>> -		     SUN6I_DPHY_GCTL_LANE_NUM(dphy->config.lanes) |
>> -		     SUN6I_DPHY_GCTL_EN);
>> -
>>  	regmap_write(dphy->regs, SUN6I_DPHY_ANA0_REG,
>>  		     SUN6I_DPHY_ANA0_REG_PWS |
>>  		     SUN6I_DPHY_ANA0_REG_DMPC |
>> @@ -244,6 +240,10 @@ static int sun6i_dphy_tx_power_on(struct sun6i_dphy *dphy)
>>  			   SUN6I_DPHY_ANA2_EN_P2S_CPU_MASK,
>>  			   SUN6I_DPHY_ANA2_EN_P2S_CPU(lanes_mask));
>>  
>> +	regmap_write(dphy->regs, SUN6I_DPHY_GCTL_REG,
>> +		     SUN6I_DPHY_GCTL_LANE_NUM(dphy->config.lanes) |
>> +		     SUN6I_DPHY_GCTL_EN);
>> +
>>  	return 0;
>>  }
>>  
>> -- 
>> 2.35.1
>>
>