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Message-ID: <03a09ff5-fe2d-3ce2-a93b-4e44fd030ffb@gmail.com>
Date: Mon, 20 Dec 2021 16:44:42 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Svyatoslav Ryhel <clamor95@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH v1] memory: tegra30-emc: Print additional memory info
20.12.2021 14:03, Krzysztof Kozlowski пишет:
> On 18/12/2021 00:47, Dmitry Osipenko wrote:
>> Print out memory type and LPDDR2 configuration on Tegra30, making it
>> similar to the memory info printed by the Tegra20 memory driver. This
>> info is useful for debugging purposes.
>>
>> Tested-by: Svyatoslav Ryhel <clamor95@...il.com> # T30 ASUS TF201 LPDDR2
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>> drivers/memory/tegra/Kconfig | 1 +
>> drivers/memory/tegra/tegra30-emc.c | 131 ++++++++++++++++++++++++++---
>> 2 files changed, 122 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/memory/tegra/Kconfig b/drivers/memory/tegra/Kconfig
>> index 7951764b4efe..3fe83d7c2bf8 100644
>> --- a/drivers/memory/tegra/Kconfig
>> +++ b/drivers/memory/tegra/Kconfig
>> @@ -28,6 +28,7 @@ config TEGRA30_EMC
>> default y
>> depends on ARCH_TEGRA_3x_SOC || COMPILE_TEST
>> select PM_OPP
>> + select DDR
>> help
>> This driver is for the External Memory Controller (EMC) found on
>> Tegra30 chips. The EMC controls the external DRAM on the board.
>> diff --git a/drivers/memory/tegra/tegra30-emc.c b/drivers/memory/tegra/tegra30-emc.c
>> index 80f98d717e13..4c0432704f46 100644
>> --- a/drivers/memory/tegra/tegra30-emc.c
>> +++ b/drivers/memory/tegra/tegra30-emc.c
>> @@ -9,6 +9,7 @@
>> * Copyright (C) 2019 GRATE-DRIVER project
>> */
>>
>> +#include <linux/bitfield.h>
>> #include <linux/clk.h>
>> #include <linux/clk/tegra.h>
>> #include <linux/debugfs.h>
>> @@ -31,11 +32,15 @@
>> #include <soc/tegra/common.h>
>> #include <soc/tegra/fuse.h>
>>
>> +#include "../jedec_ddr.h"
>> +#include "../of_memory.h"
>> +
>> #include "mc.h"
>>
>> #define EMC_INTSTATUS 0x000
>> #define EMC_INTMASK 0x004
>> #define EMC_DBG 0x008
>> +#define EMC_ADR_CFG 0x010
>> #define EMC_CFG 0x00c
>> #define EMC_REFCTRL 0x020
>> #define EMC_TIMING_CONTROL 0x028
>> @@ -81,6 +86,7 @@
>> #define EMC_EMRS 0x0d0
>> #define EMC_SELF_REF 0x0e0
>> #define EMC_MRW 0x0e8
>> +#define EMC_MRR 0x0ec
>> #define EMC_XM2DQSPADCTRL3 0x0f8
>> #define EMC_FBIO_SPARE 0x100
>> #define EMC_FBIO_CFG5 0x104
>> @@ -208,6 +214,13 @@
>>
>> #define EMC_REFRESH_OVERFLOW_INT BIT(3)
>> #define EMC_CLKCHANGE_COMPLETE_INT BIT(4)
>> +#define EMC_MRR_DIVLD_INT BIT(5)
>> +
>> +#define EMC_MRR_DEV_SELECTN GENMASK(31, 30)
>> +#define EMC_MRR_MRR_MA GENMASK(23, 16)
>> +#define EMC_MRR_MRR_DATA GENMASK(15, 0)
>> +
>> +#define EMC_ADR_CFG_EMEM_NUMDEV BIT(0)
>>
>> enum emc_dram_type {
>> DRAM_TYPE_DDR3,
>> @@ -378,6 +391,8 @@ struct tegra_emc {
>>
>> /* protect shared rate-change code path */
>> struct mutex rate_lock;
>> +
>> + bool mrr_error;
>> };
>>
>> static int emc_seq_update_timing(struct tegra_emc *emc)
>> @@ -1008,12 +1023,18 @@ static int emc_load_timings_from_dt(struct tegra_emc *emc,
>> return 0;
>> }
>>
>> -static struct device_node *emc_find_node_by_ram_code(struct device *dev)
>> +static struct device_node *emc_find_node_by_ram_code(struct tegra_emc *emc)
>> {
>> + struct device *dev = emc->dev;
>> struct device_node *np;
>> u32 value, ram_code;
>> int err;
>>
>> + if (emc->mrr_error) {
>> + dev_warn(dev, "memory timings skipped due to MRR error\n");
>> + return NULL;
>> + }
>> +
>> if (of_get_child_count(dev->of_node) == 0) {
>> dev_info_once(dev, "device-tree doesn't have memory timings\n");
>> return NULL;
>> @@ -1035,11 +1056,73 @@ static struct device_node *emc_find_node_by_ram_code(struct device *dev)
>> return NULL;
>> }
>>
>> +static int emc_read_lpddr_mode_register(struct tegra_emc *emc,
>> + unsigned int emem_dev,
>> + unsigned int register_addr,
>> + unsigned int *register_data)
>> +{
>> + u32 memory_dev = emem_dev + 1;
>> + u32 val, mr_mask = 0xff;
>> + int err;
>> +
>> + /* clear data-valid interrupt status */
>> + writel_relaxed(EMC_MRR_DIVLD_INT, emc->regs + EMC_INTSTATUS);
>> +
>> + /* issue mode register read request */
>> + val = FIELD_PREP(EMC_MRR_DEV_SELECTN, memory_dev);
>> + val |= FIELD_PREP(EMC_MRR_MRR_MA, register_addr);
>> +
>> + writel_relaxed(val, emc->regs + EMC_MRR);
>> +
>> + /* wait for the LPDDR2 data-valid interrupt */
>> + err = readl_relaxed_poll_timeout_atomic(emc->regs + EMC_INTSTATUS, val,
>> + val & EMC_MRR_DIVLD_INT,
>> + 1, 100);
>> + if (err) {
>> + dev_err(emc->dev, "mode register %u read failed: %d\n",
>> + register_addr, err);
>> + emc->mrr_error = true;
>> + return err;
>> + }
>> +
>> + /* read out mode register data */
>> + val = readl_relaxed(emc->regs + EMC_MRR);
>> + *register_data = FIELD_GET(EMC_MRR_MRR_DATA, val) & mr_mask;
>> +
>> + return 0;
>> +}
>> +
>> +static void emc_read_lpddr_sdram_info(struct tegra_emc *emc,
>> + unsigned int emem_dev)
>> +{
>> + union lpddr2_basic_config4 basic_conf4;
>> + unsigned int manufacturer_id;
>> + unsigned int revision_id1;
>> + unsigned int revision_id2;
>> +
>> + /* these registers are standard for all LPDDR JEDEC memory chips */
>> + emc_read_lpddr_mode_register(emc, emem_dev, 5, &manufacturer_id);
>> + emc_read_lpddr_mode_register(emc, emem_dev, 6, &revision_id1);
>> + emc_read_lpddr_mode_register(emc, emem_dev, 7, &revision_id2);
>> + emc_read_lpddr_mode_register(emc, emem_dev, 8, &basic_conf4.value);
>> +
>> + dev_info(emc->dev, "SDRAM[dev%u]: manufacturer: 0x%x (%s) rev1: 0x%x rev2: 0x%x prefetch: S%u density: %uMbit iowidth: %ubit\n",
>> + emem_dev, manufacturer_id,
>> + lpddr2_jedec_manufacturer(manufacturer_id),
>> + revision_id1, revision_id2,
>> + 4 >> basic_conf4.arch_type,
>> + 64 << basic_conf4.density,
>> + 32 >> basic_conf4.io_width);
>> +}
>> +
>
> Quickly looking, these two functions are exactly the same as ones in
> tegra20-emc.c
> . Later you might come up with another set for other SoCs, so it looks
> it is worth to share these.
Should be too much trouble for not much gain, IMO. How many bytes will
be shared in the end? There is no much code here, we may lose more than
win. All these Tegra EMC drivers can be compiled as a loadable modules,
that's what distro kernels usually do. There are no plans for other SoCs
for today.
I don't see how that sharing could be done easily and nicely. Please
tell if you see.
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