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From: nsekhar@ti•com (Sekhar Nori)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 5/6] ARM: davinci: remoteproc board support for OMAP-L138 DSP
Date: Tue, 4 Dec 2012 11:28:14 +0530	[thread overview]
Message-ID: <50BD90F6.4080102@ti.com> (raw)
In-Reply-To: <50BD07D8.5000305@ti.com>

On 12/4/2012 1:43 AM, Cyril Chemparathy wrote:

> On 12/03/2012 09:41 AM, Sekhar Nori wrote:

>> On 12/1/2012 7:41 AM, Tivy, Robert wrote:

>> Passing function pointers from platform code will not work when
>> converting to device tree (DT). DA850 will gain DT boot with v3.8 and
>> there is work ongoing on converting drivers to be DT-aware. Adding a new
>> driver which is DT-incompatible will not be right. Hence, I will not
>> recommend this now.

> Not sure if this solves your problem, but you could add a new clock type
> (PSC_LRESET?) as a child under the PSC clock node for the DSP. Something
> like:
> 
>   |
>   +-- PSC x (DSP0 clock)
>   |    |
>   |    +-- PSC-LRESET x (DSP0 reset control)
>   |
>   +-- PSC y (DSP1 clock)
>   |    |
>   |    +-- PSC-LRESET y (DSP1 reset control)
>   |
>   +-- PSC z (DSP2 clock)
>   |    |
>   |    +-- PSC-LRESET z (DSP2 reset control)
> 
> 
> The idea here being that if you enable the PSC clocks, you enable the
> clock gates, but leave the DSPs in reset.  On the other hand, if you
> enable the reset clock, the code implicitly enables the gate (via
> parent), and takes the DSP out of reset as well.
> 
> This is not quite the cleanest way to do it, considering that reset
> lines have no business in the clock tree, but then, this is probably the
> simplest way to fit in.  Thoughts?

This may work (on a technical level), but I am not really a fan of this
since this is essentially a hack, as you (almost) point out. It does not
model the hardware clock tree correctly and we are still struck with
using clock APIs for reset control.

I still think we need to find a better method of dealing with IP reset.
May be an acceptable method already exists. Some one needs to summarize
the problem statement well enough and I am sure finding the right
solution will not be too long drawn.

Thanks,
Sekhar

  parent reply	other threads:[~2012-12-04  5:58 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1352853207-20602-1-git-send-email-rtivy@ti.com>
2012-11-14 10:12 ` [PATCH v3 1/6] ARM: davinci: Changed pr_warning() to pr_warn() (part 1) Sergei Shtylyov
     [not found] ` <1352853207-20602-2-git-send-email-rtivy@ti.com>
2012-11-14 10:17   ` [PATCH v3 2/6] ARM: davinci: Changed pr_warning() to pr_warn() (part 2) Sergei Shtylyov
2012-11-15  1:53     ` Tivy, Robert
2012-11-15  9:46       ` Sergei Shtylyov
2012-11-20 11:27         ` Sekhar Nori
     [not found] ` <1352853207-20602-5-git-send-email-rtivy@ti.com>
2012-11-20 12:26   ` [PATCH v3 5/6] ARM: davinci: remoteproc board support for OMAP-L138 DSP Sekhar Nori
2012-11-29  1:38     ` Tivy, Robert
2012-11-30 10:50       ` Sekhar Nori
2012-12-01  2:11         ` Tivy, Robert
2012-12-03 14:41           ` Sekhar Nori
2012-12-03 20:13             ` Cyril Chemparathy
2012-12-04  2:30               ` Tivy, Robert
2012-12-04  5:58               ` Sekhar Nori [this message]
     [not found]                 ` <50BE0E54.5060607@ti.com>
     [not found]                   ` <50BE2115.4000606@ti.com>
     [not found]                     ` <13514BD7FAEBA745BBD7D8A672905C14311FB29D@DFLE08.ent.ti.com>
2012-12-05  8:35                       ` Sekhar Nori
2012-12-07  8:24                     ` Sekhar Nori
2012-12-08  1:04                       ` Tivy, Robert
2012-12-12  1:36         ` Tivy, Robert
2012-12-12 10:34           ` Sekhar Nori
2012-12-12 11:01             ` Prabhakar Lad
2012-12-12 13:06               ` Sekhar Nori
2012-12-12 13:13                 ` Prabhakar Lad
2012-12-13  8:18                   ` Prabhakar Lad
2012-12-14  8:17                     ` Sekhar Nori
2012-12-14  2:19             ` Tivy, Robert
     [not found] ` <1352853207-20602-6-git-send-email-rtivy@ti.com>
2012-11-20 12:30   ` [PATCH v3 6/6] ARM: davinci: remoteproc driver " Sekhar Nori

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