Re: [PATCH v3 06/13] OMAP3: DMA: hwmod: add system DMA

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Hi Manjunath,

On 11/3/2010 8:59 AM, G, Manjunath Kondaiah wrote:
Kevin/Benoit,

[mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of G,
Manjunath Kondaiah
Sent: Tuesday, October 26, 2010 6:55 PM

Add OMAP3 DMA hwmod structures.

Signed-off-by: G, Manjunath Kondaiah<manjugk@xxxxxx>
Cc: Benoit Cousson<b-cousson@xxxxxx>
Cc: Kevin Hilman<khilman@xxxxxxxxxxxxxxxxxxx>
Cc: Santosh Shilimkar<santosh.shilimkar@xxxxxx>
---
  arch/arm/mach-omap2/omap_hwmod_3xxx_data.c |   93
++++++++++++++++++++++++++++
  1 files changed, 93 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
index ed6bf4a..4a5231c 100644
[...]
+	.prcm = {
+		.omap2 = {
+			.prcm_reg_id		= 1,
+			.module_bit		=
OMAP3430_ST_SDMA_SHIFT,
+			.idlest_reg_id		= 1,
+			.idlest_idle_bit	=
OMAP3430_ST_SDMA_SHIFT,

Looks like the .module_offs field is missing here. Since
ST_SDMA bit belongs to CM_IDLEST1_CORE register, .module_offs should
be CORE_MOD.

But, it is observed that, using .module_offs results in warning dump
during bootup. This is due to, ST_SDMA bit in standby mode. Since
there is no fclk for DMA, this bit will never change till DMA channel
is requested for data transfer.

We might have to bypass calling "omap2_cm_wait_module_ready" in
"_wait_target_ready" in omap_hwmod.c

With exising flags, we can use "HWMOD_NO_IDLEST" flag, but this
flag has different meaning. How about using new flag like
"HWMOD_NO_FCLK_OPCLK" and if it is set, return without calling
"omap2_cm_wait_module_ready"

Any better suggestion to handle this issue?

Well, yes, use HWMOD_NO_IDLEST and remove idlest_reg_id & idlest_idle_bit entries in the omap2 structure.

ST_SDMA is the standby status of the SDMA, but there is no idle status on that IP, so you cannot do anything. The standby will just reflect the activity of the master port of the DMA, but it will give you no information about the slave port and thus we do not have any module ready information.

Regards,
Benoit
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