From: Detlev Zundel <dzu@denx•de>
To: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH v4 1/5] fsl-diu-fb: fix issue with re-enabling DIU area descriptor
Date: Thu, 29 Jul 2010 13:48:02 +0200 [thread overview]
Message-ID: <m2fwz2fr0t.fsf@ohwell.denx.de> (raw)
In-Reply-To: AANLkTikkLVCxU4ZC_nmUhKTQogUNeQzxOX6KqgZcxiYr__2540.83384429595$1280300644$gmane$org@mail.gmail.com
Hi Grant,
> On Fri, Jul 23, 2010 at 8:00 AM, Anatolij Gustschin <agust@denx•de> wrote:
>> On MPC5121e Rev 2.0 re-configuring the DIU area descriptor
>> by writing new descriptor address doesn't always work.
>> As a result, DIU continues to display using old area descriptor
>> even if the new one has been written to the descriptor register of
>> the plane.
>>
>> Add the code from Freescale MPC5121EADS BSP for writing descriptor
>> addresses properly. This fixes the problem for Rev 2.0 silicon.
>>
>> Signed-off-by: Anatolij Gustschin <agust@denx•de>
>> ---
>> v4:
>> - use workaround code as suggested by FSL technical support.
>>
>> v3:
>> - no changes since v1
>>
>> drivers/video/fsl-diu-fb.c | 38 +++++++++++++++++++++++---------------
>> 1 files changed, 23 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/video/fsl-diu-fb.c b/drivers/video/fsl-diu-fb.c
>> index 27455ce..9b8c991 100644
>> --- a/drivers/video/fsl-diu-fb.c
>> +++ b/drivers/video/fsl-diu-fb.c
>> @@ -317,6 +317,17 @@ static void fsl_diu_free(void *virt, size_t size)
>> free_pages_exact(virt, size);
>> }
>>
>> +/*
>> + * Workaround for failed writing desc register of planes.
>> + * Needed with MPC5121 DIU rev 2.0 silicon.
>> + */
>> +void wr_reg_wa(u32 *reg, u32 val)
>> +{
>> + do {
>> + out_be32(reg, val);
>> + } while (in_be32(reg) != val);
>> +}
>
> I'll apply this one, but it looks like a potential problem. What
> happens if the write never succeeds? The kernel then gets stuck in a
> forever busy loop. You should look at reworking it.
We would surely like to do this "the correct way(tm)". Unfortunately
this commit reflects what we have been told by Freescale support and it
fixes a real observed problem. We fail to find a better solution
without any insight into the internal workings of the functional block.
Cheers
Detlev
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu@denx•de
next prev parent reply other threads:[~2010-07-29 11:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-23 14:00 [PATCH v4 0/5] Rework MPC5121 DIU support (for 2.6.36) Anatolij Gustschin
2010-07-23 14:00 ` [PATCH v4 1/5] fsl-diu-fb: fix issue with re-enabling DIU area descriptor Anatolij Gustschin
2010-07-28 7:02 ` Grant Likely
2010-07-28 7:56 ` Anatolij Gustschin
[not found] ` <AANLkTikkLVCxU4ZC_nmUhKTQogUNeQzxOX6KqgZcxiYr__2540.83384429595$1280300644$gmane$org@mail.gmail.com>
2010-07-29 11:48 ` Detlev Zundel [this message]
2010-07-23 14:00 ` [PATCH v4 2/5] fsl-diu-fb: move fsl-diu-fb.h to include/linux Anatolij Gustschin
2010-07-23 14:00 ` [PATCH v4 3/5] powerpc/mpc5121: shared DIU framebuffer support Anatolij Gustschin
2010-07-23 14:00 ` [PATCH v4 4/5] powerpc: doc/dts-bindings: update doc of FSL DIU bindings Anatolij Gustschin
2010-07-23 14:00 ` [PATCH v4 5/5] fsl-diu-fb: Support setting display mode using EDID Anatolij Gustschin
2010-12-16 16:47 ` Timur Tabi
2010-12-16 16:53 ` Grant Likely
2010-12-16 16:55 ` Timur Tabi
2010-12-16 17:06 ` Grant Likely
2010-12-16 17:28 ` Timur Tabi
2010-12-16 17:42 ` Grant Likely
2010-12-16 17:42 ` Anatolij Gustschin
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