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Message-ID: <20150106142412.GL31830@ulmo.nvidia.com>
Date: Tue, 6 Jan 2015 15:24:15 +0100
From: Thierry Reding <thierry.reding@...il.com>
To: Vince Hsu <vinceh@...dia.com>
Cc: Lucas Stach <dev@...xeye.de>, swarren@...dotorg.org,
gnurou@...il.com, bskeggs@...hat.com, martin.peres@...e.fr,
seven@...rod-online.com, samuel.pitoiset@...il.com,
nouveau@...ts.freedesktop.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH nouveau 06/11] platform: complete the power up/down
sequence
On Tue, Jan 06, 2015 at 10:19:49PM +0800, Vince Hsu wrote:
> On 02:55:52PM Jan 06, Thierry Reding wrote:
> > * PGP Signed by an unknown key
> >
> > On Tue, Jan 06, 2015 at 08:13:01PM +0800, Vince Hsu wrote:
> > >
> > > On 01/06/2015 07:36 PM, Thierry Reding wrote:
> > > >> Old Signed by an unknown key
> > > >
> > > >On Tue, Jan 06, 2015 at 05:34:01PM +0800, Vince Hsu wrote:
> > > >>On 01/05/2015 11:25 PM, Thierry Reding wrote:
> > > >>>>Old Signed by an unknown key
> > > >>>On Thu, Dec 25, 2014 at 10:42:58AM +0800, Vince Hsu wrote:
> > > >>>>On 12/24/2014 09:23 PM, Lucas Stach wrote:
> > > >>>>>Am Dienstag, den 23.12.2014, 18:39 +0800 schrieb Vince Hsu:
> > > >>>>>>This patch adds some missing pieces of the rail gaing/ungating sequence that
> > > >>>>>>can improve the stability in theory.
> > > >>>>>>
> > > >>>>>>Signed-off-by: Vince Hsu <vinceh@...dia.com>
> > > >>>>>>---
> > > >>>>>> drm/nouveau_platform.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> > > >>>>>> drm/nouveau_platform.h | 3 +++
> > > >>>>>> 2 files changed, 45 insertions(+)
> > > >>>>>>
> > > >>>>>>diff --git a/drm/nouveau_platform.c b/drm/nouveau_platform.c
> > > >>>>>>index 68788b17a45c..527fe2358fc9 100644
> > > >>>>>>--- a/drm/nouveau_platform.c
> > > >>>>>>+++ b/drm/nouveau_platform.c
> > > >>>>>>@@ -25,9 +25,11 @@
> > > >>>>>> #include <linux/module.h>
> > > >>>>>> #include <linux/platform_device.h>
> > > >>>>>> #include <linux/of.h>
> > > >>>>>>+#include <linux/of_platform.h>
> > > >>>>>> #include <linux/reset.h>
> > > >>>>>> #include <linux/regulator/consumer.h>
> > > >>>>>> #include <soc/tegra/fuse.h>
> > > >>>>>>+#include <soc/tegra/mc.h>
> > > >>>>>> #include <soc/tegra/pmc.h>
> > > >>>>>> #include "nouveau_drm.h"
> > > >>>>>>@@ -61,6 +63,9 @@ static int nouveau_platform_power_up(struct nouveau_platform_gpu *gpu)
> > > >>>>>> reset_control_deassert(gpu->rst);
> > > >>>>>> udelay(10);
> > > >>>>>>+ tegra_mc_flush(gpu->mc, gpu->swgroup, false);
> > > >>>>>>+ udelay(10);
> > > >>>>>>+
> > > >>>>>> return 0;
> > > >>>>>> err_clamp:
> > > >>>>>>@@ -77,6 +82,14 @@ static int nouveau_platform_power_down(struct nouveau_platform_gpu *gpu)
> > > >>>>>> {
> > > >>>>>> int err;
> > > >>>>>>+ tegra_mc_flush(gpu->mc, gpu->swgroup, true);
> > > >>>>>>+ udelay(10);
> > > >>>>>>+
> > > >>>>>>+ err = tegra_powergate_gpu_set_clamping(true);
> > > >>>>>>+ if (err)
> > > >>>>>>+ return err;
> > > >>>>>>+ udelay(10);
> > > >>>>>>+
> > > >>>>>> reset_control_assert(gpu->rst);
> > > >>>>>> udelay(10);
> > > >>>>>>@@ -91,6 +104,31 @@ static int nouveau_platform_power_down(struct nouveau_platform_gpu *gpu)
> > > >>>>>> return 0;
> > > >>>>>> }
> > > >>>>>>+static int nouveau_platform_get_mc(struct device *dev,
> > > >>>>>>+ struct tegra_mc **mc, unsigned int *swgroup)
> > > >>>>>Uhm, no. If this is needed this has to be a Tegra MC function and not
> > > >>>>>burried into nouveau code. You are using knowledge about the internal
> > > >>>>>workings of the MC driver here.
> > > >>>>>
> > > >>>>>Also this should probably only take the Dt node pointer as argument and
> > > >>>>>return a something like a tegra_mc_client struct that contains both the
> > > >>>>>MC device pointer and the swgroup so you can pass that to
> > > >>>>>tegra_mc_flush().
> > > >>>>Good idea. I will have something as below in V2 if there is no other
> > > >>>>comments for this.
> > > >>>>
> > > >>>>tegra_mc_client *tegra_mc_find_client(struct device_node *node)
> > > >>>>{
> > > >>>> ...
> > > >>>> ret = of_parse_phandle_with_args(node, "nvidia,memory-client", ...)
> > > >>>> ...
> > > >>>>}
> > > >>>>
> > > >>>>There were some discussion about this few weeks ago. I'm not sure whether we
> > > >>>>have some conclusion/implementation though. Thierry?
> > > >>>>
> > > >>>>http://lists.infradead.org/pipermail/linux-arm-kernel/2014-December/308703.html
> > > >>>I don't think client is a good fit here. Flushing is done per SWGROUP
> > > >>>(on all clients of the SWGROUP). So I think we'll want something like:
> > > >>>
> > > >>> gpu@0,57000000 {
> > > >>> ...
> > > >>> nvidia,swgroup = <&mc TEGRA_SWGROUP_GPU>;
> > > >>> ...
> > > >>> };
> > > >>>
> > > >>>In the DT and return a struct tegra_mc_swgroup along the lines of:
> > > >>>
> > > >>> struct tegra_mc_client {
> > > >>> unsigned int id;
> > > >>> unsigned int swgroup;
> > > >>>
> > > >>> struct list_head list;
> > > >>> };
> > > >>>
> > > >>> struct tegra_mc_swgroup {
> > > >>> struct list_head clients;
> > > >>> unsigned int id;
> > > >>> };
> > > >>>
> > > >>>Where tegra_mc_swgroup.clients is a list of struct tegra_mc_client
> > > >>>structures, each representing a memory client pertaining to the
> > > >>>SWGROUP.
> > > >>Based on your suggestion above, I created a struct tegra_mc_swgroup:
> > > >>
> > > >>struct tegra_mc_swgroup {
> > > >> unsigned int id;
> > > >> struct tegra_mc *mc;
> > > >> struct list_head head;
> > > >> struct list_head clients;
> > > >>};
> > > >>
> > > >>And added the list head in the struct tegra_mc_soc.
> > > >>
> > > >>struct tegra_mc_soc {
> > > >> struct tegra_mc_client *clients;
> > > >> unsigned int num_clients;
> > > >>
> > > >> struct tegra_mc_hr *hr_clients;
> > > >> unsigned int num_hr_clients;
> > > >Why do you still need these?
> > > This part is added in "[PATCH 2/11] memory: tegra: add mc flush support" and
> > > "[PATCH 3/11] memory: tegra: add flush operation for Tegra124 memory
> > > clients"
> > > for the hotreset registers.
> >
> > Right. Perhaps calling this structure tegra_mc_hotreset and the
> > variables *_hotresets would be a good idea to clarify that they aren't
> > actually per-client but per-SWGROUP.
> Okay.
>
> >
> > > >>Created one function to build the swgroup list.
> > > >>
> > > >>static int tegra_mc_build_swgroup(struct tegra_mc *mc)
> > > >>{
> > > >> int i;
> > > >>
> > > >> for (i = 0; i < mc->soc->num_clients; i++) {
> > > >> struct tegra_mc_swgroup *sg;
> > > >> bool found = false;
> > > >>
> > > >> list_for_each_entry(sg, &mc->soc->swgroups, head) {
> > > >> if (sg->id == mc->soc->clients[i].swgroup) {
> > > >> found = true;
> > > >> break;
> > > >> }
> > > >> }
> > > >Can't you use your new tegra_mc_find_swgroup() function here? That way
> > > >you could turn it into something slightly more readable:
> > > The tegra_mc_build_swgroup() is called during driver probe, and after that
> > > the swgroup list is established and then the tegra_mc_find_swgroup() can
> > > work.
> >
> > But you can reuse tegra_mc_find_swgroup() instead of open-coding it to
> > search the partial list. The code will be exactly the same, won't it?
> That depends on how you define the tegra_mc_find_swgroup().
>
> >
> > > > unsigned int swgroup = mc->soc->clients[i].swgroup;
> > > > struct tegra_mc_swgroup *group;
> > > >
> > > > group = tegra_mc_find_swgroup(mc, swgroup);
> > > The tegra_mc_find_swgroup() is expected to be called outside the mc driver
> > > and
> > > can only take the device node as argument because other drivers do not have
> > > the mc instance information unless they call tegra_mc_find_swgroup() or
> > > tegra_mc_find_client().
> >
> > You can do that by making a low-level function that works on the struct
> > tegra_mc * and an unsigned int swgroup which is only used internally and
> > then wrap a public function around it that deals with looking up the
> > struct tegra_mc * and SWGROUP ID.
> Now the tegra_mc_find_swgroup() looks like below:
>
> struct tegra_mc_swgroup *tegra_mc_find_swgroup(struct device_node *node)
> {
> struct of_phandle_args args;
> struct platform_device *pdev;
> struct tegra_mc *mc;
> struct tegra_mc_swgroup *sg;
> int ret;
>
> ret = of_parse_phandle_with_fixed_args(node, "nvidia,swgroup",
> 1, 0, &args);
> if (ret)
> return ERR_PTR(ret);
>
> pdev = of_find_device_by_node(args.np);
> if (!pdev)
> return NULL;
>
> mc = platform_get_drvdata(pdev);
> if (!mc)
> return NULL;
>
> list_for_each_entry(sg, &mc->soc->swgroups, head) {
> if (sg->id == args.args[0])
> return sg;
> }
>
> return NULL;
> }
> EXPORT_SYMBOL(tegra_mc_find_swgroup);
>
> I will add a find_swgroup() as internal funcion and add the add_swgroup()
> per your suggestion. And keep the tegra_mc_find_swgroup() public. Is that
> okay for you?
Sounds good.
Thierry
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