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Date: Tue, 6 Jan 2015 17:34:01 +0800
From: Vince Hsu <vinceh@...dia.com>
To: Thierry Reding <thierry.reding@...il.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 01/05/2015 11:25 PM, Thierry Reding wrote:
> * PGP 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;
struct list_head swgroups;
...
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;
}
}
if (!found) {
sg = devm_kzalloc(mc->dev, sizeof(*sg), GFP_KERNEL);
if (!sg)
return -ENOMEM;
sg->id = mc->soc->clients[i].swgroup;
sg->mc = mc;
list_add_tail(&sg->head, &mc->soc->swgroups);
INIT_LIST_HEAD(&sg->clients);
}
list_add_tail(&mc->soc->clients[i].head, &sg->clients);
}
return 0;
}
>
> We probably don't want to expose these structures publicly, an opaque
> type should be enough. Then you can use functions like:
>
> struct tegra_mc_swgroup *tegra_mc_find_swgroup(struct device_node *node);
And then I can use the tegra_find_swgroup() in GK20A driver to get the
swgroup
and flush the memory clients by tegra_mc_flush(swgroup).
One problem is that the mc_soc and mc_clients are are defined as const.
To build
the swgroup list dynamically, I have to discard the const. I guess you
won't like that. :(
Thanks,
Vince
> At some point we may even need something like:
>
> struct tegra_mc_client *tegra_mc_find_client(struct device_node *node,
> const char *name);
>
> And DT content like this:
>
> gpu@0,57000000 {
> ...
> nvidia,memory-clients = <&mc 0x58>, <&mc 0x59>;
> nvidia,memory-client-names = "read", "write";
> ...
> };
>
> This could be useful for latency allowance programming, but we can cross
> that bridge when we come to it.
>
> Thierry
>
> * Unknown Key
> * 0x7F3EB3A1
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