From: peter.ujfalusi@ti•com (Péter Ujfalusi)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv2 12/12] ARM: OMAP4: hwmod data: do not enable or reset the McPDM during kernel init
Date: Tue, 30 Oct 2012 08:41:01 +0100 [thread overview]
Message-ID: <508F848D.3070609@ti.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1210300403170.12697@utopia.booyaka.com>
Hi Paul,
On 10/30/2012 05:05 AM, Paul Walmsley wrote:
> omap_hwmod: mcpdm: cannot be enabled for reset (3)
>
> The McPDM on OMAP4 can only receive its functional clock from an
> off-chip source. This source is not guaranteed to be present on the
> board, and when present, it is controlled by I2C. This would
> introduce a board dependency to the early hwmod code which it was not
> designed to handle. Also, neither the driver for this off-chip clock
> provider nor the I2C code is available early in boot when the hwmod
> code is attempting to enable and reset IP blocks. This effectively
> makes it impossible to enable and reset this device during hwmod init.
>
> At its core, this patch is a workaround for an OMAP hardware problem.
> It should be possible to configure the OMAP to provide any IP block's
> functional clock from an on-chip source. (This is true for almost
> every IP block on the chip. As far as I know, McPDM is the only
> exception.) If the kernel cannot reset and configure IP blocks, it
> cannot guarantee a sane SoC state. Relying on an optional off-chip
> clock also creates a board dependency which is beyond the scope of the
> early hwmod code.
>
> This patch works around the issue by marking the McPDM hwmod record
> with the HWMOD_EXT_OPT_MAIN_CLK flag. This prevents the hwmod
> code from touching the device early during boot.
>
> Signed-off-by: Paul Walmsley <paul@pwsan•com>
> Cc: P?ter Ujfalusi <peter.ujfalusi@ti•com>
> Cc: Beno?t Cousson <b-cousson@ti•com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti•com>
> ---
> arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
> index 652d028..7bddfa5 100644
> --- a/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
> +++ b/arch/arm/mach-omap2/omap_hwmod_44xx_data.c
> @@ -2125,6 +2125,14 @@ static struct omap_hwmod omap44xx_mcpdm_hwmod = {
> .name = "mcpdm",
> .class = &omap44xx_mcpdm_hwmod_class,
> .clkdm_name = "abe_clkdm",
> + /*
> + * It's suspected that the McPDM requires an off-chip main
> + * functional clock, controlled via I2C. This IP block is
> + * currently reset very early during boot, before I2C is
> + * available, so it doesn't seem that we have any choice in
> + * the kernel other than to avoid resetting it.
> + */
> + .flags = HWMOD_EXT_OPT_MAIN_CLK,
> .mpu_irqs = omap44xx_mcpdm_irqs,
> .sdma_reqs = omap44xx_mcpdm_sdma_reqs,
> .main_clk = "mcpdm_fck",
>
--
P?ter
prev parent reply other threads:[~2012-10-30 7:41 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-11 0:45 [PATCHv2 00/12] ARM: OMAP: core/hwmod: first set of fixes for 3.5-rc Paul Walmsley
2012-06-11 0:45 ` [PATCHv2 01/12] ARM: OMAP: PM: Lock clocks list while generating summary Paul Walmsley
2012-06-11 0:45 ` [PATCHv2 02/12] ARM: OMAP2+: hwmod code/data: fix 32K sync timer Paul Walmsley
2012-06-14 16:47 ` Cousson, Benoit
2012-06-14 18:04 ` Paul Walmsley
2012-06-14 20:13 ` Cousson, Benoit
2012-06-15 0:18 ` Paul Walmsley
2012-06-15 13:28 ` Cousson, Benoit
2012-07-04 12:48 ` Paul Walmsley
2012-07-04 12:53 ` Paul Walmsley
2012-07-04 14:27 ` Kevin Hilman
2012-07-04 14:53 ` Paul Walmsley
2012-07-04 16:14 ` Benoit Cousson
2012-07-04 16:41 ` Tero Kristo
2012-07-04 16:43 ` Benoit Cousson
2012-07-04 19:02 ` Paul Walmsley
2012-07-04 16:57 ` Benoit Cousson
2012-07-04 18:59 ` Paul Walmsley
2012-07-05 22:06 ` Kevin Hilman
2012-07-04 16:01 ` Benoit Cousson
2012-07-04 19:05 ` Paul Walmsley
2012-06-11 0:46 ` [PATCHv2 03/12] ARM: OMAP4+: hwmod: fix issue causing IPs not going back to Smart-Standby Paul Walmsley
2012-06-11 0:46 ` [PATCHv2 04/12] ARM: OMAP4: hwmod data: fix 32k sync timer idle modes Paul Walmsley
2012-06-11 9:31 ` Cousson, Benoit
2012-06-13 17:22 ` Paul Walmsley
2012-06-11 0:46 ` [PATCHv2 05/12] ARM: OMAP2+: hwmod: add setup_preprogram hook Paul Walmsley
2012-06-11 0:46 ` [PATCHv2 06/12] ARM: OMAP2+: hwmod: add flag to prevent hwmod code from touching IP block during init Paul Walmsley
2012-06-11 0:46 ` [PATCHv2 07/12] ARM: OMAP4+: AESS: enable internal auto-gating during initial setup Paul Walmsley
2012-06-11 6:29 ` Tony Lindgren
2012-06-14 9:49 ` Paul Walmsley
2012-06-14 9:59 ` Tony Lindgren
2012-06-11 0:46 ` [PATCHv2 08/12] ARM: OMAP4: hwmod data: add SL2IF hardreset line Paul Walmsley
2012-06-14 12:55 ` Cousson, Benoit
2012-06-14 17:09 ` Paul Walmsley
2012-06-14 21:07 ` Cousson, Benoit
2012-06-14 23:02 ` Paul Walmsley
2012-06-15 9:11 ` Cousson, Benoit
2012-06-11 0:46 ` [PATCHv2 09/12] ARM: OMAP2+: usb_host_fs: add custom setup_preprogram for usb_host_fs (fsusb) Paul Walmsley
2012-06-11 6:34 ` Tony Lindgren
2012-06-11 7:13 ` Felipe Balbi
2012-06-11 7:41 ` Tony Lindgren
2012-06-11 7:48 ` Felipe Balbi
2012-06-11 8:03 ` Tony Lindgren
2012-06-11 9:12 ` Felipe Balbi
2012-06-11 0:46 ` [PATCHv2 10/12] ARM: OMAP2+: CM: increase the module disable timeout Paul Walmsley
2012-06-11 0:46 ` [PATCHv2 11/12] ARM: OMAP4: clock data: add clockdomains for clocks used as main clocks Paul Walmsley
2012-06-11 16:28 ` Cousson, Benoit
2012-06-11 16:59 ` Paul Walmsley
2012-06-11 20:15 ` Cousson, Benoit
2012-06-11 0:46 ` [PATCHv2 12/12] ARM: OMAP4: hwmod data: do not enable or reset the McPDM during kernel init Paul Walmsley
2012-06-11 9:54 ` Cousson, Benoit
2012-10-30 4:05 ` Paul Walmsley
2012-10-30 7:41 ` Péter Ujfalusi [this message]
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