linux-kernel - Re: [Linux-stm32] [PATCH v8 08/10] drm: stm: dw-mipi-dsi: let the bridge handle the HW version check

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Message-ID: <87blm387vt.fsf@iwork.i-did-not-set--mail-host-address--so-tickle-me>
Date:   Mon, 01 Jun 2020 12:15:02 +0300
From:   Adrian Ratiu <adrian.ratiu@...labora.com>
To:     Philippe CORNU <philippe.cornu@...com>,
        Adrian Ratiu <adrian.ratiu@...labora.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-rockchip@...ts.infradead.org" 
        <linux-rockchip@...ts.infradead.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>
Cc:     Jernej Skrabec <jernej.skrabec@...l.net>,
        Heiko Stuebner <heiko@...ech.de>,
        Adrian Pop <pop.adrian61@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        "linux-imx@....com" <linux-imx@....com>,
        "kernel@...labora.com" <kernel@...labora.com>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        Arnaud Ferraris <arnaud.ferraris@...labora.com>,
        Yannick FERTRE <yannick.fertre@...com>,
        Benjamin GAIGNARD <benjamin.gaignard@...com>
Subject: Re: [Linux-stm32] [PATCH v8 08/10] drm: stm: dw-mipi-dsi: let the
 bridge handle the HW version check

On Fri, 29 May 2020, Philippe CORNU <philippe.cornu@...com> wrote:
> Hi Adrian, and thank you very much for the patchset.  Thank you 
> also for having tested it on STM32F769 and STM32MP1.  Sorry for 
> the late response, Yannick and I will review it as soon as 
> possible and we will keep you posted.  Note: Do not hesitate to 
> put us in copy for the next version  (philippe.cornu@...com, 
> yannick.fertre@...com) Regards, Philippe :-) 

Hi Philippe,

Thank you very much for your previous and future STM testing, 
really appreciate it! I've CC'd Yannick until now but I'll also CC 
you sure :)

It's been over a month since I posted v8 and I was just gearing up 
to address all feedback, rebase & retest to prepare v9 but I'll 
wait a little longer, no problem, it's no rush.

Have an awesome day,
Adrian

>
>
> On 4/27/20 10:19 AM, Adrian Ratiu wrote:
>> The stm mipi-dsi platform driver added a version test in
>> commit fa6251a747b7 ("drm/stm: dsi: check hardware version")
>> so that HW revisions other than v1.3x get rejected. The rockchip
>> driver had no such check and just assumed register layouts are
>> v1.3x compatible.
>> 
>> Having such tests was a good idea because only v130/v131 layouts
>> were supported at the time, however since adding multiple layout
>> support in the bridge, the version is automatically checked for
>> all drivers, compatible layouts get picked and unsupported HW is
>> automatically rejected by the bridge, so there's no use keeping
>> the test in the stm driver.
>> 
>> The main reason prompting this change is that the stm driver
>> test immediately disabled the peripheral clock after reading
>> the version, making the bridge read version 0x0 immediately
>> after in its own probe(), so we move the clock disabling after
>> the bridge does the version test.
>> 
>> Tested on STM32F769 and STM32MP1.
>> 
>> Cc: linux-stm32@...md-mailman.stormreply.com
>> Reported-by: Adrian Pop <pop.adrian61@...il.com>
>> Tested-by: Adrian Pop <pop.adrian61@...il.com>
>> Tested-by: Arnaud Ferraris <arnaud.ferraris@...labora.com>
>> Signed-off-by: Adrian Ratiu <adrian.ratiu@...labora.com>
>> ---
>> New in v6.
>> ---
>>   drivers/gpu/drm/stm/dw_mipi_dsi-stm.c | 12 +++---------
>>   1 file changed, 3 insertions(+), 9 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>> index 2e1f2664495d0..7218e405d7e2b 100644
>> --- a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>> +++ b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>> @@ -402,15 +402,6 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
>>   		goto err_dsi_probe;
>>   	}
>>   
>> -	dsi->hw_version = dsi_read(dsi, DSI_VERSION) & VERSION;
>> -	clk_disable_unprepare(pclk);
>> -
>> -	if (dsi->hw_version != HWVER_130 && dsi->hw_version != HWVER_131) {
>> -		ret = -ENODEV;
>> -		DRM_ERROR("bad dsi hardware version\n");
>> -		goto err_dsi_probe;
>> -	}
>> -
>>   	dw_mipi_dsi_stm_plat_data.base = dsi->base;
>>   	dw_mipi_dsi_stm_plat_data.priv_data = dsi;
>>   
>> @@ -423,6 +414,9 @@ static int dw_mipi_dsi_stm_probe(struct platform_device *pdev)
>>   		goto err_dsi_probe;
>>   	}
>>   
>> +	dsi->hw_version = dsi_read(dsi, DSI_VERSION) & VERSION;
>> +	clk_disable_unprepare(pclk);
>> +
>>   	return 0;
>>   
>>   err_dsi_probe:
>>