Messages in this thread | | | Date | Fri, 13 Jan 2023 17:45:44 +0530 | Subject | Re: [Patch v1 01/10] memory: tegra: add interconnect support for DRAM scaling in Tegra234 | From | Sumit Gupta <> |
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On 21/12/22 22:13, Dmitry Osipenko wrote: > External email: Use caution opening links or attachments > > > 21.12.2022 12:35, Sumit Gupta пишет: >> >> >> On 20/12/22 23:40, Dmitry Osipenko wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> 20.12.2022 19:02, Sumit Gupta пишет: >>>> +static int tegra_emc_icc_get_init_bw(struct icc_node *node, u32 >>>> *avg, u32 *peak) >>>> +{ >>>> + *avg = 0; >>>> + *peak = 0; >>>> + >>>> + return 0; >>>> +} >>> >>> Looks wrong, you should add ICC support to all the drivers first and >>> only then enable ICC. I think you added this init_bw() to work around >>> the fact that ICC isn't supported by T234 drivers. >> >> If get_bw hook is not added then max freq is set due to 'INT_MAX' below. >> >> void icc_node_add(struct icc_node *node, struct icc_provider *provider) >> { >> .... >> /* get the initial bandwidth values and sync them with hardware */ >> if (provider->get_bw) { >> provider->get_bw(node, &node->init_avg, &node->init_peak); >> } else { >> node->init_avg = INT_MAX; >> node->init_peak = INT_MAX; >> } >> >> So, will have to add the empty functions at least. >> >> static int tegra_emc_icc_get_init_bw(struct icc_node *node, u32 *avg, >> u32 *peak) >> { >> - *avg = 0; >> - *peak = 0; >> - >> return 0; >> } >> >> Support to all the client drivers can't be added at once as there are >> many drivers all with different requirements and handling. This patch >> series is the beginning to add the basic interconnect support in new >> Tegra SoC's. Support for more clients will be added later one by one or >> in batch. > > This means that bandwidth management isn't working properly. You should > leave the freq to INT_MAX and fix the missing integer overflows in the > code if any, or read out the BW from FW. > > Once you'll enable ICC for all drivers, it will start working. >
Referred the below patches and now understand what you mean.
https://patchwork.kernel.org/project/linux-arm-msm/cover/20200825170152.6434-1-georgi.djakov@linaro.org/ https://lore.kernel.org/all/20210912183009.6400-1-digetx@gmail.com/
There is no MRQ currently in BPMP-FW to get the bandwidth for a client. So, can't add that in get_bw(). As explained earlier, we are in process adding of adding support for all clients but that may take some time. We can remove the get_bw() calls initializing "*bw = 0" once we have the support added in all clients. Noticed that below drivers also do same.
$ grep -rB3 "*peak = 0" drivers/interconnect/* drivers/interconnect/imx/imx.c-static int imx_icc_get_bw(struct icc_node *node, u32 *avg, u32 *peak) drivers/interconnect/imx/imx.c-{ drivers/interconnect/imx/imx.c- *avg = 0; drivers/interconnect/imx/imx.c: *peak = 0; -- drivers/interconnect/qcom/msm8974.c-static int msm8974_get_bw(struct icc_node *node, u32 *avg, u32 *peak) drivers/interconnect/qcom/msm8974.c-{ drivers/interconnect/qcom/msm8974.c- *avg = 0; drivers/interconnect/qcom/msm8974.c: *peak = 0;
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