Re: [RFC v3 1/2] mmc: sdhci-msm: Add interconnect bus bandwidth scaling support
From: ppvk
Date: Wed Feb 12 2020 - 10:10:54 EST
Hi Matthias,
Thanks for the review !
On 2020-02-08 06:12, Matthias Kaehlcke wrote:
Hi Pradeep,
On Fri, Feb 07, 2020 at 08:14:54PM +0530, Pradeep P V K wrote:
Add interconnect bandwidths for SDHC driver using OPP framework that
is required by SDHC driver based on the clock frequency and bus width
of the card. Otherwise, the system clocks may run at minimum clock
speed and thus affecting the performance.
This change is based on Georgi Djakov [RFC]
(https://lkml.org/lkml/2018/10/11/499) and
Saravana Kannan [PATCH v6]
(https://lkml.org/lkml/2019/12/6/740)
change from RFC v2 -> v3 changes:
- Modified interconnect bandwidth support using OPP framework.
- Addressed review comments on v2.
Signed-off-by: Sahitya Tummala <stummala@xxxxxxxxxxxxxx>
Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@xxxxxxxxxxxxxx>
Co-developed-by: Pradeep P V K <ppvk@xxxxxxxxxxxxxx>
Signed-off-by: Pradeep P V K <ppvk@xxxxxxxxxxxxxx>
---
drivers/mmc/host/sdhci-msm.c | 251
++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 247 insertions(+), 4 deletions(-)
diff --git a/drivers/mmc/host/sdhci-msm.c
b/drivers/mmc/host/sdhci-msm.c
index 71f29ba..f061cd8 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -11,8 +11,10 @@
#include <linux/mmc/mmc.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
+#include <linux/interconnect.h>
#include <linux/iopoll.h>
#include <linux/regulator/consumer.h>
+#include <linux/pm_opp.h>
#include "sdhci-pltfm.h"
@@ -229,6 +231,14 @@ struct sdhci_msm_variant_info {
const struct sdhci_msm_offset *offset;
};
+struct sdhci_msm_bus_vote_data {
+
+ struct icc_path *sdhc_to_ddr;
+ struct icc_path *cpu_to_sdhc;
+ bool skip_bus_bw_voting;
nit: the name is somewhat redundant given the name of the containing
struct. 'skip_vote' or 'skip_voting' would be sufficient IMO.
ok. i will address in my next patch series.
+ u32 curr_freq;
+};
+
struct sdhci_msm_host {
struct platform_device *pdev;
void __iomem *core_mem; /* MSM SDCC mapped address */
@@ -255,8 +265,11 @@ struct sdhci_msm_host {
bool use_cdr;
u32 transfer_mode;
bool updated_ddr_cfg;
+ struct sdhci_msm_bus_vote_data *bus_vote_data;
};
+static void sdhci_msm_bus_voting(struct sdhci_host *host, u32
enable);
+
static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct
sdhci_host *host)
{
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -1564,6 +1577,7 @@ static void sdhci_msm_set_clock(struct
sdhci_host *host, unsigned int clock)
msm_set_clock_rate_for_bus_mode(host, clock);
out:
+ sdhci_msm_bus_voting(host, !!clock);
__sdhci_msm_set_clock(host, clock);
}
@@ -1685,6 +1699,219 @@ static void
sdhci_msm_set_regulator_caps(struct sdhci_msm_host *msm_host)
pr_debug("%s: supported caps: 0x%08x\n", mmc_hostname(mmc), caps);
}
+/*
+ * Returns required bandwidth in Bytes per Sec
+ */
+static unsigned long sdhci_get_bw_required(struct sdhci_host *host,
+ struct mmc_ios *ios)
+{
+ unsigned long bw;
+ struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+ struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
+
+ bw = msm_host->clk_rate;
nit: you could declare 'bw' last and do the assignment together with
the
declaration.
ok. I will do it in my next patch.
+
+ if (ios->bus_width == MMC_BUS_WIDTH_4)
+ bw /= 2;
+ else if (ios->bus_width == MMC_BUS_WIDTH_1)
+ bw /= 8;
+
+ return bw;
+}
+
+/*
+ * Helper function to parse the exact OPP node
+ * Returns OPP pointer on success else NULL on error
+ */
+static struct dev_pm_opp *find_opp_for_freq(struct sdhci_msm_host
*msm_host,
+ unsigned long bw)
+{
+ struct dev_pm_opp *opp;
+ struct sdhci_host *host = mmc_priv(msm_host->mmc);
+ unsigned int freq = bw;
+ struct device *dev = &msm_host->pdev->dev;
+
+
+ if (!freq)
+ opp = dev_pm_opp_find_peak_bw_floor(dev, &freq);
+ else
+ opp = dev_pm_opp_find_peak_bw_exact(dev, freq, true);
+
+ /* Max Bandwidth vote */
s/Bandwidth/bandwidth/
ok.
+ if (PTR_ERR(opp) == -ERANGE && freq > sdhci_msm_get_max_clock(host))
+ opp = dev_pm_opp_find_peak_bw_ceil(dev, &bw);
+
+ if (IS_ERR(opp)) {
+ dev_err(dev, "Failed to find OPP for freq:%u err:%ld\n",
+ freq, PTR_ERR(opp));
+ return NULL;
+ }
+ return opp;
+}
+
+/*
+ * This function sets the interconnect bus bandwidth
+ * vote based on bw (bandwidth) argument.
+ */
+#define BUS_INTERCONNECT_PATHS 2 /* 1. sdhc -> ddr 2. cpu -> sdhc */
+static void sdhci_msm_bus_set_vote(struct sdhci_host *host,
+ unsigned int bw)
+{
+ int i;
+ struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+ struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
+ struct sdhci_msm_bus_vote_data *vote_data = msm_host->bus_vote_data;
+ struct dev_pm_opp *opp;
+ unsigned long freq = bw;
+ unsigned long ib[BUS_INTERCONNECT_PATHS],
ab[BUS_INTERCONNECT_PATHS];
the names are not very expressive, how about peak_bw and avg_bw?
hmm, ok. i will modify in my next patch set.
+ int ddr_rc = 0, cpu_rc = 0;
initialization is not needed
ok.
+
+ if (!msm_host->bus_vote_data->sdhc_to_ddr ||
+ !msm_host->bus_vote_data->cpu_to_sdhc)
+ return;
+
+ if (bw != vote_data->curr_freq) {
if (bw == vote_data->curr_freq)
return;
+ for (i = 0; i < BUS_INTERCONNECT_PATHS; i++) {
+ opp = find_opp_for_freq(msm_host, freq);
+ if (opp) {
+ ab[i] = dev_pm_opp_get_bw(opp, &ib[i]);
+ freq += 1; /* Next Band width vote */
s/Band width/bandwidth/
ok.
+ dev_pm_opp_put(opp);
+ }
+ }
+ pr_debug("%s: freq:%d sdhc_to_ddr ab:%lu ib:%lu cpu_to_sdhc ab:%lu
ib:%lu\n",
+ mmc_hostname(host->mmc), bw, ab[0], ib[0],
+ ab[1], ib[1]);
+ ddr_rc = icc_set_bw(vote_data->sdhc_to_ddr, 0, ib[0]);
+ cpu_rc = icc_set_bw(vote_data->cpu_to_sdhc, 0, ib[1]);
+ if (ddr_rc || cpu_rc) {
+ pr_err("%s: icc_set() failed ddr_rc_err:%d cpu_rc_err:%d\n",
+ mmc_hostname(host->mmc), ddr_rc, cpu_rc);
+ return;
+ }
+ vote_data->curr_freq = bw;
+ }
+}
+
+/*
+ * This function registers the device to OPP framework and
+ * parses few optional parameters from the device tree node.
+ * Returns NULL bvd pointer on error else a valid bvd pointer.
+ */
+static struct sdhci_msm_bus_vote_data
*sdhci_msm_get_bus_vote_data(struct device
+ *dev, struct sdhci_msm_host *host)
+
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct sdhci_msm_bus_vote_data *vote_data = NULL;
+ int ret = 0;
initialization of 'vote_data' and 'ret' is not needed.
ok. i will be removing this function and bring all the required to the
caller function
that should address all the comments on this function.
+
+ if (!pdev) {
+ dev_err(dev, "Null platform device!\n");
+ return NULL;
+ }
It's probably safe to assume that the device is a platform device?
same as above.
+ vote_data = devm_kzalloc(dev, sizeof(*vote_data), GFP_KERNEL);
+ if (!vote_data)
+ return vote_data;
return ERR_PTR(-ENOMEM); ?
+
+ ret = dev_pm_opp_of_add_table(dev);
+ if (ret) {
+ if (ret == -ENODEV || ret == -ENODATA) {
+ dev_dbg(dev, "OPP not found. Skip bus voting!!:%d\n",
+ ret);
+ vote_data->skip_bus_bw_voting = true;
+ } else {
+ dev_dbg(dev, "OPP regestration failed:%d\n", ret);
s/regestration/registration/
ok.
Depending on the consequences of this failure (e.g. probe() fails) you
probably want to use dev_warn() or dev_err() here.
same as above.
+ goto err;
+ }
+ }
+
+ return vote_data;
+err:
+ devm_kfree(dev, vote_data);
+ vote_data = NULL;
not needed
ok.
+ return vote_data;
return NULL;
+}
+
+/*
+ * Helper function to register for OPP and interconnect
+ * frameworks.
+ */
+static int sdhci_msm_bus_register(struct sdhci_msm_host *host,
+ struct platform_device *pdev)
+{
+ struct sdhci_msm_bus_vote_data *vote_data;
+ struct device *dev = &pdev->dev;
+ int ret = 0;
+
+ vote_data = sdhci_msm_get_bus_vote_data(dev, host);
+ if (!vote_data) {
+ dev_dbg(&pdev->dev, "Failed to get bus_scale data\n");
In general I'm not convinced about the use of dev_dbg() in the error
paths. Maybe there is some signal you can use to determine if there
should be a valid bus scaling information (e.g. some DT property
exists). If it exists you proceed with obtaining the necessary
information and complain loudly if something goes wrong, otherwise you
don't even try to obtain it and omit the debug logs.
ok. i will modify accordingly, in my next patch series.
+ host->bus_vote_data = NULL;
IIUC struct sdhci_msm_host is zero initialized by sdhci_pltfm_init(),
hence the assignment to NULL is not needed.
ok.
+ return -EINVAL;
Use the error returned by sdhci_msm_get_bus_vote_data().
ok. i will address in my next patch set.
+ }
+ host->bus_vote_data = vote_data;
+
+ vote_data->sdhc_to_ddr = of_icc_get(&pdev->dev, "sdhc-ddr");
This could be the signal I mentioned above. If this entry does not
exist it is pointless to proceed. You could check this before
sdhci_msm_get_bus_vote_data() and abort with a dev_info() message in
case it doesn't exist. If it exists any error afterwards will be
reported with dev_err().
ok. i will modify the code accordingly in my next patch series.
+ if (!vote_data->sdhc_to_ddr) {
+ dev_dbg(&pdev->dev, "DT property for path %s missing\n",
+ "sdhc-ddr");
+ return -ENOENT;
+ } else if (IS_ERR(vote_data->sdhc_to_ddr) {
+ dev_dbg(&pdev->dev, "(%ld): failed getting %s path\n",
+ PTR_ERR(vote_data->sdhc_to_ddr), "sdhc-ddr");
+ ret = PTR_ERR(vote_data->sdhc_to_ddr);
+ vote_data->sdhc_to_ddr = NULL;
+ return ret;
if there is an error probe() should probably be aborted. If that's the
case you can replace the above three lines with 'return
PTR_ERR(vote_data->sdhc_to_ddr);'
True but i added this for more cautious. Any how it is handled as error
probe().
i will address this in my next patch series.
+ }
+ vote_data->cpu_to_sdhc = of_icc_get(&pdev->dev, "cpu-sdhc");
+ if (!vote_data->cpu_to_sdhc) {
+ dev_dbg(&pdev->dev, "DT property for path %s missing\n",
+ "cpu_to_sdhc");
+ return -ENOENT;
+ } else if (IS_ERR(vote_data->cpu_to_sdhc)) {
+ dev_dbg(&pdev->dev, "(%ld): failed getting %s path\n",
+ PTR_ERR(vote_data->cpu_to_sdhc), "cpu-sdhc");
+ ret = PTR_ERR(vote_data->cpu_to_sdhc);
+ vote_data->cpu_to_sdhc = NULL;
+ return ret;
same comment as above
ok. i will take care this too.
+ }
+ return ret;
no error if we get to this point, hence:
return 0;
ok.
+}
+
+static void sdhci_msm_bus_unregister(struct device *dev,
+ struct sdhci_msm_host *host)
+{
+ struct sdhci_msm_bus_vote_data *vote_data = host->bus_vote_data;
+
+ if (vote_data->skip_bus_bw_voting ||
+ !vote_data->sdhc_to_ddr ||
+ !vote_data->cpu_to_sdhc)
+ return;
+
+ icc_put(vote_data->sdhc_to_ddr);
+ icc_put(vote_data->cpu_to_sdhc);
+}
+
+#define MSM_MMC_BUS_VOTING_DELAY 200 /* msecs */
+
+static void sdhci_msm_bus_voting(struct sdhci_host *host, u32 enable)
s/u32/bool/ ?
ok.
+{
+ struct mmc_ios *ios = &host->mmc->ios;
+ struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+ struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
+ unsigned int bw;
+
+ if (msm_host->bus_vote_data->skip_bus_bw_voting)
+ return;
+
+ if (enable) {
+ bw = sdhci_get_bw_required(host, ios);
+ sdhci_msm_bus_set_vote(host, bw);
+ } else
+ sdhci_msm_bus_set_vote(host, 0);
+}
+
static const struct sdhci_msm_variant_ops mci_var_ops = {
.msm_readl_relaxed = sdhci_msm_mci_variant_readl_relaxed,
.msm_writel_relaxed = sdhci_msm_mci_variant_writel_relaxed,
@@ -1845,11 +2072,20 @@ static int sdhci_msm_probe(struct
platform_device *pdev)
dev_warn(&pdev->dev, "TCXO clk not present (%d)\n", ret);
}
+ ret = sdhci_msm_bus_register(msm_host, pdev);
+ if (ret && msm_host->bus_vote_data &&
+ !msm_host->bus_vote_data->skip_bus_bw_voting) {
+ dev_err(&pdev->dev, "Bus registration failed (%d)\n", ret);
+ goto clk_disable;
+ }
+
+ sdhci_msm_bus_voting(host, 1);
s/1/true/
ok.
+
if (!msm_host->mci_removed) {
msm_host->core_mem = devm_platform_ioremap_resource(pdev, 1);
if (IS_ERR(msm_host->core_mem)) {
ret = PTR_ERR(msm_host->core_mem);
- goto clk_disable;
+ goto bus_unregister;
}
}
@@ -1924,7 +2160,7 @@ static int sdhci_msm_probe(struct
platform_device *pdev)
msm_host->pwr_irq = platform_get_irq_byname(pdev, "pwr_irq");
if (msm_host->pwr_irq < 0) {
ret = msm_host->pwr_irq;
- goto clk_disable;
+ goto bus_unregister;
}
sdhci_msm_init_pwr_irq_wait(msm_host);
@@ -1937,7 +2173,7 @@ static int sdhci_msm_probe(struct
platform_device *pdev)
dev_name(&pdev->dev), host);
if (ret) {
dev_err(&pdev->dev, "Request IRQ failed (%d)\n", ret);
- goto clk_disable;
+ goto bus_unregister;
}
pm_runtime_get_noresume(&pdev->dev);
@@ -1962,6 +2198,9 @@ static int sdhci_msm_probe(struct
platform_device *pdev)
pm_runtime_disable(&pdev->dev);
pm_runtime_set_suspended(&pdev->dev);
pm_runtime_put_noidle(&pdev->dev);
+bus_unregister:
+ sdhci_msm_bus_voting(host, 0);
s/0/false/
ok.
+ sdhci_msm_bus_unregister(&pdev->dev, msm_host);
clk_disable:
clk_bulk_disable_unprepare(ARRAY_SIZE(msm_host->bulk_clks),
msm_host->bulk_clks);
@@ -1991,6 +2230,9 @@ static int sdhci_msm_remove(struct
platform_device *pdev)
msm_host->bulk_clks);
if (!IS_ERR(msm_host->bus_clk))
clk_disable_unprepare(msm_host->bus_clk);
+
+ sdhci_msm_bus_voting(host, 0);
s/0/false/
ok.
+ sdhci_msm_bus_unregister(&pdev->dev, msm_host);
sdhci_pltfm_free(pdev);
return 0;
}
@@ -2003,7 +2245,7 @@ static __maybe_unused int
sdhci_msm_runtime_suspend(struct device *dev)
clk_bulk_disable_unprepare(ARRAY_SIZE(msm_host->bulk_clks),
msm_host->bulk_clks);
-
+ sdhci_msm_bus_voting(host, 0);
s/0/false/
ok.
return 0;
}
@@ -2025,6 +2267,7 @@ static __maybe_unused int
sdhci_msm_runtime_resume(struct device *dev)
if (msm_host->restore_dll_config && msm_host->clk_rate)
return sdhci_msm_restore_sdr_dll_config(host);
+ sdhci_msm_bus_voting(host, 1);
s/0/true/
ok. i will address all these in my next patch series.
Thanks
Matthias