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From: Joonyoung Shim <jy0922.shim@samsung.com>
To: Sean Paul <seanpaul@chromium.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>,
	Tomasz Stanislawski <t.stanislaws@samsung.com>,
	"kgene.kim" <kgene.kim@samsung.com>,
	devicetree-discuss@lists.ozlabs.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	dri-devel@lists.freedesktop.org,
	Tomasz Figa <tomasz.figa@gmail.com>,
	linux-samsung-soc@vger.kernel.org,
	Sylwester Nawrocki <sylvester.nawrocki@gmail.com>,
	Olof Johansson <olofj@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	RAHUL SHARMA <rahul.sharma@samsung.com>
Subject: Re: [PATCH v3 1/3] drm/exynos: Get HDMI version from device tree
Date: Wed, 06 Feb 2013 10:48:21 +0900	[thread overview]
Message-ID: <5111B665.7000006@samsung.com> (raw)
In-Reply-To: <CAOw6vbKhsWp7VnqgvECd-P4e5okX6dwKn3P8+phfpG29rA+h7g@mail.gmail.com>

On 02/06/2013 09:56 AM, Sean Paul wrote:
> On Tue, Feb 5, 2013 at 4:42 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 02/05/2013 05:37 PM, Sean Paul wrote:
>>> On Tue, Feb 5, 2013 at 4:22 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>>>> n 02/05/2013 04:42 PM, Sean Paul wrote:
>>>>> Use the compatible string in the device tree to determine which
>>>>> registers/functions to use in the HDMI driver. Also changes the
>>>>> references from v13 to 4210 and v14 to 4212 to reflect the IP
>>>>> block version instead of the HDMI version.
>>>>> diff --git a/Documentation/devicetree/bindings/drm/exynos/hdmi.txt b/Documentation/devicetree/bindings/drm/exynos/hdmi.txt
>>>> Binding looks sane to me.
>>>>
>>>>> diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
>>>>>   #ifdef CONFIG_OF
>>>>>   static struct of_device_id hdmi_match_types[] = {
>>>>>        {
>>>>> -             .compatible = "samsung,exynos5-hdmi",
>>>>> -             .data   = (void *)HDMI_TYPE14,
>>>>> +             .compatible = "samsung,exynos4-hdmi",
>>>>>        }, {
>>>>>                /* end node */
>>>>>        }
>>>> Why not fill in all the "base" compatible values there (I think you need
>>>> this anyway so that DTs don't all have to be compatible with
>>>> samsung,exynos4-hdmi), with .data containing the HDMI_VER_EXYNOS*
>>>> values, then ...
>>>>
>>> At the moment, all DTs have to be compatible with exynos4-hdmi since
>>> it provides the base for the current driver. The driver uses 4210 and
>>> 4212 to differentiate between different register addresses and
>>> features, but most things are just exynos4-hdmi compatible.
>> The DT nodes should include only the compatible values that the HW is
>> actually compatible with. If the HW isn't compatible with exynos4-hdmi,
>> that value shouldn't be in the compatible property, but instead whatever
>> the "base" value that the HW really is compatible with. The driver can
>> support multiple "base" compatible values from this table.
>>
> All devices that use this driver are compatible, at some level, with
> exynos4-hdmi, so I think its usage is correct here.
>
>>>>> @@ -2218,17 +2217,18 @@ static int hdmi_probe(struct platform_device *pdev)
>>>>> +
>>>>> +     if (of_device_is_compatible(dev->of_node, "samsung,exynos4210-hdmi"))
>>>>> +             hdata->version |= HDMI_VER_EXYNOS4210;
>>>>> +     if (of_device_is_compatible(dev->of_node, "samsung,exynos4212-hdmi"))
>>>>> +             hdata->version |= HDMI_VER_EXYNOS4212;
>>>>> +     if (of_device_is_compatible(dev->of_node, "samsung,exynos5250-hdmi"))
>>>>> +             hdata->version |= HDMI_VER_EXYNOS5250;

But this way can make unnecessary combinations, e.g. exynos4210-hdmi + 
exynos5250-hdmi.

>>>> Instead of that, do roughly:
>>>>
>>>>      match = of_match_device(hdmi_match_types, &pdev->dev);
>>>>      if (match)
>>>>          hdata->version |= (int)match->data;
>>>>
>>>> That way, it's all table-based. Any future additions to
>>>> hdmi_match_types[] won't require another if statement to be added to
>>>> probe().
>>> I don't think it's that easy. of_match_device returns the first match
>>> from the device table, so I'd still need to iterate through the
>>> matches. I could still break this out into a table, but I don't think
>>> of_match_device is the right way to probe it.
>> You shouldn't have to iterate over multiple matches. of_match_device()
>> is supposed to return the match for the first entry in the compatible
>> property, then if there was no match, move on to looking at the next
>> entry in the compatible property, etc. In practice, I think it's still
>> not implemented quite correctly for this, but you can make it work by
>> putting the newest compatible value first in the match table.
> I think the only way that works is if you hardcode the compatible
> versions in the driver, like this:
>
> static struct of_device_id hdmi_match_types[] = {
>          {
>                  .compatible = "samsung,exynos5250-hdmi",
>                  .data = (void *)(HDMI_VER_EXYNOS5250 | HDMI_VER_EXYNOS4212);
>          }, {
>                  .compatible = "samsung,exynos4212-hdmi",
>                  .data = (void *)HDMI_VER_EXYNOS4212;
>          }, {
>                  .compatible = "samsung,exynos4210-hdmi",
>                  .data = (void *)HDMI_VER_EXYNOS4210;
>          }, {
>                  /* end node */
>          }
> };

I think this makes driver more clearly. We just see device tables and we 
can know device uses which version.

>
> In that case, it eliminates the benefit of using device tree to
> determine the compatible bits. I hope I'm just being thick and missing
> something.
>
> Sean
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>


WARNING: multiple messages have this Message-ID
From: jy0922.shim@samsung.com (Joonyoung Shim)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 1/3] drm/exynos: Get HDMI version from device tree
Date: Wed, 06 Feb 2013 10:48:21 +0900	[thread overview]
Message-ID: <5111B665.7000006@samsung.com> (raw)
In-Reply-To: <CAOw6vbKhsWp7VnqgvECd-P4e5okX6dwKn3P8+phfpG29rA+h7g@mail.gmail.com>

On 02/06/2013 09:56 AM, Sean Paul wrote:
> On Tue, Feb 5, 2013 at 4:42 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 02/05/2013 05:37 PM, Sean Paul wrote:
>>> On Tue, Feb 5, 2013 at 4:22 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>>>> n 02/05/2013 04:42 PM, Sean Paul wrote:
>>>>> Use the compatible string in the device tree to determine which
>>>>> registers/functions to use in the HDMI driver. Also changes the
>>>>> references from v13 to 4210 and v14 to 4212 to reflect the IP
>>>>> block version instead of the HDMI version.
>>>>> diff --git a/Documentation/devicetree/bindings/drm/exynos/hdmi.txt b/Documentation/devicetree/bindings/drm/exynos/hdmi.txt
>>>> Binding looks sane to me.
>>>>
>>>>> diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
>>>>>   #ifdef CONFIG_OF
>>>>>   static struct of_device_id hdmi_match_types[] = {
>>>>>        {
>>>>> -             .compatible = "samsung,exynos5-hdmi",
>>>>> -             .data   = (void *)HDMI_TYPE14,
>>>>> +             .compatible = "samsung,exynos4-hdmi",
>>>>>        }, {
>>>>>                /* end node */
>>>>>        }
>>>> Why not fill in all the "base" compatible values there (I think you need
>>>> this anyway so that DTs don't all have to be compatible with
>>>> samsung,exynos4-hdmi), with .data containing the HDMI_VER_EXYNOS*
>>>> values, then ...
>>>>
>>> At the moment, all DTs have to be compatible with exynos4-hdmi since
>>> it provides the base for the current driver. The driver uses 4210 and
>>> 4212 to differentiate between different register addresses and
>>> features, but most things are just exynos4-hdmi compatible.
>> The DT nodes should include only the compatible values that the HW is
>> actually compatible with. If the HW isn't compatible with exynos4-hdmi,
>> that value shouldn't be in the compatible property, but instead whatever
>> the "base" value that the HW really is compatible with. The driver can
>> support multiple "base" compatible values from this table.
>>
> All devices that use this driver are compatible, at some level, with
> exynos4-hdmi, so I think its usage is correct here.
>
>>>>> @@ -2218,17 +2217,18 @@ static int hdmi_probe(struct platform_device *pdev)
>>>>> +
>>>>> +     if (of_device_is_compatible(dev->of_node, "samsung,exynos4210-hdmi"))
>>>>> +             hdata->version |= HDMI_VER_EXYNOS4210;
>>>>> +     if (of_device_is_compatible(dev->of_node, "samsung,exynos4212-hdmi"))
>>>>> +             hdata->version |= HDMI_VER_EXYNOS4212;
>>>>> +     if (of_device_is_compatible(dev->of_node, "samsung,exynos5250-hdmi"))
>>>>> +             hdata->version |= HDMI_VER_EXYNOS5250;

But this way can make unnecessary combinations, e.g. exynos4210-hdmi + 
exynos5250-hdmi.

>>>> Instead of that, do roughly:
>>>>
>>>>      match = of_match_device(hdmi_match_types, &pdev->dev);
>>>>      if (match)
>>>>          hdata->version |= (int)match->data;
>>>>
>>>> That way, it's all table-based. Any future additions to
>>>> hdmi_match_types[] won't require another if statement to be added to
>>>> probe().
>>> I don't think it's that easy. of_match_device returns the first match
>>> from the device table, so I'd still need to iterate through the
>>> matches. I could still break this out into a table, but I don't think
>>> of_match_device is the right way to probe it.
>> You shouldn't have to iterate over multiple matches. of_match_device()
>> is supposed to return the match for the first entry in the compatible
>> property, then if there was no match, move on to looking at the next
>> entry in the compatible property, etc. In practice, I think it's still
>> not implemented quite correctly for this, but you can make it work by
>> putting the newest compatible value first in the match table.
> I think the only way that works is if you hardcode the compatible
> versions in the driver, like this:
>
> static struct of_device_id hdmi_match_types[] = {
>          {
>                  .compatible = "samsung,exynos5250-hdmi",
>                  .data = (void *)(HDMI_VER_EXYNOS5250 | HDMI_VER_EXYNOS4212);
>          }, {
>                  .compatible = "samsung,exynos4212-hdmi",
>                  .data = (void *)HDMI_VER_EXYNOS4212;
>          }, {
>                  .compatible = "samsung,exynos4210-hdmi",
>                  .data = (void *)HDMI_VER_EXYNOS4210;
>          }, {
>                  /* end node */
>          }
> };

I think this makes driver more clearly. We just see device tables and we 
can know device uses which version.

>
> In that case, it eliminates the benefit of using device tree to
> determine the compatible bits. I hope I'm just being thick and missing
> something.
>
> Sean
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>

  reply	other threads:[~2013-02-06  1:48 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-05 23:42 [PATCH v3 0/2] Get the HDMI IP block " Sean Paul
2013-02-05 23:42 ` Sean Paul
2013-02-05 23:42 ` [PATCH v3 1/3] drm/exynos: Get HDMI " Sean Paul
2013-02-05 23:42   ` Sean Paul
2013-02-06  0:22   ` Stephen Warren
2013-02-06  0:22     ` Stephen Warren
2013-02-06  0:37     ` Sean Paul
2013-02-06  0:37       ` Sean Paul
2013-02-06  0:37       ` Sean Paul
2013-02-06  0:42       ` Stephen Warren
2013-02-06  0:42         ` Stephen Warren
2013-02-06  0:47         ` Kyungmin Park
2013-02-06  0:47           ` Kyungmin Park
2013-02-06  0:56         ` Sean Paul
2013-02-06  0:56           ` Sean Paul
2013-02-06  1:48           ` Joonyoung Shim [this message]
2013-02-06  1:48             ` Joonyoung Shim
2013-02-06  2:49           ` Stephen Warren
2013-02-06  2:49             ` Stephen Warren
2013-02-06  2:56           ` 김승우
2013-02-06  2:56             ` 김승우
2013-02-06 19:01             ` Olof Johansson
2013-02-06 19:01               ` Olof Johansson
2013-02-05 23:42 ` [PATCH v3 2/3] ARM: Change exynos5-hdmi references to exynos4-hdmi Sean Paul
2013-02-05 23:42   ` Sean Paul

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