Re: [PATCH v9 01/17] memory: tegra30: Support interconnect framework

Georgi Djakov
2020-11-17T20:24:43Z

Hi Dmitry,

Thank you working on this!

On 15.11.20 23:29, Dmitry Osipenko wrote:
> Now Internal and External memory controllers are memory interconnection
> providers. This allows us to use interconnect API for tuning of memory
> configuration. EMC driver now supports OPPs and DVFS. MC driver now
> supports tuning of memory arbitration latency, which needs to be done
> for ISO memory clients, like a Display client for example.
>
> Tested-by: Peter Geis <pgwipeout@gmail.com>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/memory/tegra/Kconfig | 1 +
> drivers/memory/tegra/tegra30-emc.c | 349 +++++++++++++++++++++++++++--
> drivers/memory/tegra/tegra30.c | 173 +++++++++++++-
> 3 files changed, 501 insertions(+), 22 deletions(-)
>
[..]> diff --git a/drivers/memory/tegra/tegra30.c
b/drivers/memory/tegra/tegra30.c
> index d0314f29608d..ea849003014b 100644
> --- a/drivers/memory/tegra/tegra30.c
> +++ b/drivers/memory/tegra/tegra30.c
[..]
> +
> +static int tegra30_mc_icc_set(struct icc_node *src, struct icc_node *dst)
> +{
> + struct tegra_mc *mc = icc_provider_to_tegra_mc(src->provider);
> + const struct tegra_mc_client *client = &mc->soc->clients[src->id];
> + u64 peak_bandwidth = icc_units_to_bps(src->peak_bw);
> +
> + /*
> + * Skip pre-initialization that is done by icc_node_add(), which sets
> + * bandwidth to maximum for all clients before drivers are loaded.
> + *
> + * This doesn't make sense for us because we don't have drivers for all
> + * clients and it's okay to keep configuration left from bootloader
> + * during boot, at least for today.
> + */
> + if (src == dst)
> + return 0;

Nit: The "proper" way to express this should be to implement the
.get_bw() callback to return zero as initial average/peak bandwidth.
I'm wondering if this will work here?

The rest looks good to me!

Thanks,
Georgi