Re: [PATCH v4 12/13] mmc: mmci: add explicit clk control
From: Srinivas Kandagatla
Date: Fri May 30 2014 - 06:39:34 EST
Thanks Ulf for reviewing.
On 30/05/14 11:25, Ulf Hansson wrote:
On 28 May 2014 15:47, <srinivas.kandagatla@xxxxxxxxxx> wrote:
From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
On Controllers like Qcom SD card controller where cclk is mclk and mclk should
be directly controlled by the driver.
This patch adds support to control mclk directly in the driver, and also
adds explicit_mclk_control flag in variant structure giving more flexibility
to the driver.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
drivers/mmc/host/mmci.c | 96 ++++++++++++++++++++++++++++++++-----------------
drivers/mmc/host/mmci.h | 2 ++
2 files changed, 65 insertions(+), 33 deletions(-)
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 202f2d5..6eb0a29 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -72,6 +72,7 @@ static unsigned int fmax = 515633;
* @pwrreg_clkgate: MMCIPOWER register must be used to gate the clock
* @busy_detect: true if busy detection on dat0 is supported
* @pwrreg_nopower: bits in MMCIPOWER don't controls ext. power supply
+ * @explicit_mclk_control: enable explicit mclk control in driver.
*/
struct variant_data {
unsigned int clkreg;
@@ -93,6 +94,7 @@ struct variant_data {
bool pwrreg_clkgate;
bool busy_detect;
bool pwrreg_nopower;
+ bool explicit_mclk_control;
};
static struct variant_data variant_arm = {
@@ -199,6 +201,7 @@ static struct variant_data variant_qcom = {
.datalength_bits = 24,
.pwrreg_powerup = MCI_PWR_UP,
.f_max = 208000000,
+ .explicit_mclk_control = true,
This should go in patch3 instead.
yes.. will get this in to the patch3 too.
};
static int mmci_card_busy(struct mmc_host *mmc)
@@ -301,7 +304,9 @@ static void mmci_set_clkreg(struct mmci_host *host, unsigned int desired)
host->cclk = 0;
if (desired) {
- if (desired >= host->mclk) {
+ if (variant->explicit_mclk_control) {
+ host->cclk = host->mclk;
+ } else if (desired >= host->mclk) {
clk = MCI_CLK_BYPASS;
if (variant->st_clkdiv)
clk |= MCI_ST_UX500_NEG_EDGE;
@@ -1340,6 +1345,18 @@ static void mmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
if (!ios->clock && variant->pwrreg_clkgate)
pwr &= ~MCI_PWR_ON;
+ if ((host->variant->explicit_mclk_control) &&
+ (ios->clock != host->mclk_req)) {
+ int rc = clk_set_rate(host->clk, ios->clock);
+ if (rc < 0) {
+ dev_err(mmc_dev(host->mmc),
+ "Error setting clock rate (%d)\n", rc);
+ } else {
+ host->mclk = clk_get_rate(host->clk);
+ host->mclk_req = ios->clock;
+ }
+ }
+
spin_lock_irqsave(&host->lock, flags);
mmci_set_clkreg(host, ios->clock);
@@ -1490,19 +1507,6 @@ static int mmci_probe(struct amba_device *dev,
host->plat = plat;
host->variant = variant;
host->mclk = clk_get_rate(host->clk);
- /*
- * According to the spec, mclk is max 100 MHz,
- * so we try to adjust the clock down to this,
- * (if possible).
- */
- if (host->mclk > host->variant->f_max) {
- ret = clk_set_rate(host->clk, host->variant->f_max);
- if (ret < 0)
- goto clk_disable;
- host->mclk = clk_get_rate(host->clk);
- dev_dbg(mmc_dev(mmc), "eventual mclk rate: %u Hz\n",
- host->mclk);
- }
The above code is relevant for Qcom as well, I don't think you need
change/move it.
Yes, you are right. I will fix it in next version.
host->phybase = dev->res.start;
host->base = devm_ioremap_resource(&dev->dev, &dev->res);
@@ -1511,25 +1515,51 @@ static int mmci_probe(struct amba_device *dev,
goto clk_disable;
}
- /*
- * The ARM and ST versions of the block have slightly different
- * clock divider equations which means that the minimum divider
- * differs too.
- */
- if (variant->st_clkdiv)
- mmc->f_min = DIV_ROUND_UP(host->mclk, 257);
I think you could simplify the change of fixing with f_min and f_max.
Start by, just add another statement here "else if
(variant->explicit_mclk_control)" and do the clk_round_rate()
- else
- mmc->f_min = DIV_ROUND_UP(host->mclk, 512);
- /*
- * If no maximum operating frequency is supplied, fall back to use
- * the module parameter, which has a (low) default value in case it
- * is not specified. Either value must not exceed the clock rate into
- * the block, of course.
- */
- if (mmc->f_max)
- mmc->f_max = min(host->mclk, mmc->f_max);
- else
- mmc->f_max = min(host->mclk, fmax);
Further replace the above with:
if (mmc->f_max)
mmc->f_max = variant->explicit_mclk_control ? min(mmc->f_max,
variant->f_max) : min(host->mclk, mmc->f_max);
else
mmc->f_max = variant->explicit_mclk_control ? fmax : min(host->mclk, fmax);
That should do it, right?
yes, that will work. It simplifies the logic too.
+ if (variant->explicit_mclk_control) {
+ /* get the nearest minimum clock to 100Khz */
+ mmc->f_min = clk_round_rate(host->clk, 100000);
+
+ if (mmc->f_max)
+ mmc->f_max = min(host->variant->f_max, mmc->f_max);
+ else
+ mmc->f_max = min(host->variant->f_max, fmax);
+
+ } else {
+ /*
+ * According to the spec, mclk is max 100 MHz,
+ * so we try to adjust the clock down to this,
+ * (if possible).
+ */
+ if (host->mclk > host->variant->f_max) {
+ ret = clk_set_rate(host->clk, host->variant->f_max);
+ if (ret < 0)
+ goto clk_disable;
+ host->mclk = clk_get_rate(host->clk);
+ dev_dbg(mmc_dev(mmc), "eventual mclk rate: %u Hz\n",
+ host->mclk);
+ }
+ /*
+ * The ARM and ST versions of the block have slightly different
+ * clock divider equations which means that the minimum divider
+ * differs too.
+ */
+ if (variant->st_clkdiv)
+ mmc->f_min = DIV_ROUND_UP(host->mclk, 257);
+ else
+ mmc->f_min = DIV_ROUND_UP(host->mclk, 512);
+ /*
+ * If no maximum operating frequency is supplied, fall back to
+ * use the module parameter, which has a (low) default value in
+ * case it is not specified. Either value must not exceed the
+ * clock rate into the block, of course.
+ */
+ if (mmc->f_max)
+ mmc->f_max = min(host->mclk, mmc->f_max);
+ else
+ mmc->f_max = min(host->mclk, fmax);
+
+ }
+
dev_dbg(mmc_dev(mmc), "clocking block at %u Hz\n", mmc->f_max);
/* Get regulators and the supported OCR mask */
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 706eb513..1882e20 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -208,6 +208,8 @@ struct mmci_host {
spinlock_t lock;
unsigned int mclk;
+ /* cached value of requested clk in set_ios */
+ unsigned int mclk_req;
How about "clock_cache" instead?
Sounds ok to me, I will change it in next version.
Thanks,
srini
unsigned int cclk;
u32 pwr_reg;
u32 pwr_reg_add;
--
1.9.1
Kind regards
Ulf Hansson
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