From: Chris Ball <cjb@laptop.org>
To: Seungwon Jeon <tgih.jun@samsung.com>
Cc: "'Doug Anderson'" <dianders@chromium.org>,
linux-mmc@vger.kernel.org,
"'Will Newton'" <will.newton@imgtec.com>,
"'James Hogan'" <james.hogan@imgtec.com>,
"'Jaehoon Chung'" <jh80.chung@samsung.com>,
linux-kernel@vger.kernel.org,
"'Grant Grundler'" <grundler@chromium.org>,
"'Olof Johansson'" <olofj@chromium.org>,
shashidharh@vayavyalabs.com, ki0351.kim@samsung.com
Subject: Re: [PATCH v4] mmc: dw_mmc: Disable low power mode if SDIO interrupts are used
Date: Tue, 07 Aug 2012 23:40:59 -0400 [thread overview]
Message-ID: <87obmmvyno.fsf@octavius.laptop.org> (raw)
In-Reply-To: <000501cd6ae3$33beb8b0$9b3c2a10$%jun@samsung.com> (Seungwon Jeon's message of "Thu, 26 Jul 2012 13:00:31 +0900")
Hi,
On Thu, Jul 26 2012, Seungwon Jeon wrote:
> July 26, 2012, Doug Anderson <dianders@chromium.org> wrote:
>> The documentation for the dw_mmc part says that the low power
>> mode should normally only be set for MMC and SD memory and should
>> be turned off for SDIO cards that need interrupts detected.
>>
>> The best place I could find to do this is when the SDIO interrupt
>> was first enabled. I rely on the fact that dw_mci_setup_bus()
>> will be called when it's time to reenable.
>>
>> Signed-off-by: Doug Anderson <dianders@chromium.org>
>> ---
>> Changes in v4:
>> - Don't regenerate slot variable when we already had it.
>>
>> Changes in v3:
>> - Commenting fixes requested by Seungwoon Jeon and Jaehoon Chung.
>> - Only pass 'slot' to the low power disable function since whole mmc
>> structure wasn't needed.
>>
>> Changes in v2:
>> - Commenting fixes requested by Grant Grundler.
>> - Be extra certain that we don't re-turn on the low power mode in
>> CLKENA in dw_mci_setup_bus() if SDIO interrupts are enabled.
>> There are no known instances of this happening but it's good to be safe.
>>
>> drivers/mmc/host/dw_mmc.c | 41 ++++++++++++++++++++++++++++++++++++++---
>> 1 files changed, 38 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 72dc3cd..882748b 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -627,6 +627,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot)
>> {
>> struct dw_mci *host = slot->host;
>> u32 div;
>> + u32 clk_en_a;
>>
>> if (slot->clock != host->current_speed) {
>> div = host->bus_hz / slot->clock;
>> @@ -659,9 +660,11 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot)
>> mci_send_cmd(slot,
>> SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
>>
>> - /* enable clock */
>> - mci_writel(host, CLKENA, ((SDMMC_CLKEN_ENABLE |
>> - SDMMC_CLKEN_LOW_PWR) << slot->id));
>> + /* enable clock; only low power if no SDIO */
>> + clk_en_a = SDMMC_CLKEN_ENABLE << slot->id;
>> + if (!(mci_readl(host, INTMASK) & SDMMC_INT_SDIO(slot->id)))
>> + clk_en_a |= SDMMC_CLKEN_LOW_PWR << slot->id;
>> + mci_writel(host, CLKENA, clk_en_a);
>>
>> /* inform CIU */
>> mci_send_cmd(slot,
>> @@ -862,6 +865,30 @@ static int dw_mci_get_cd(struct mmc_host *mmc)
>> return present;
>> }
>>
>> +/*
>> + * Disable lower power mode.
>> + *
>> + * Low power mode will stop the card clock when idle. According to the
>> + * description of the CLKENA register we should disable low power mode
>> + * for SDIO cards if we need SDIO interrupts to work.
>> + *
>> + * This function is fast if low power mode is already disabled.
>> + */
>> +static void dw_mci_disable_low_power(struct dw_mci_slot *slot)
>> +{
>> + struct dw_mci *host = slot->host;
>> + u32 clk_en_a;
>> + const u32 clken_low_pwr = SDMMC_CLKEN_LOW_PWR << slot->id;
>> +
>> + clk_en_a = mci_readl(host, CLKENA);
>> +
>> + if (clk_en_a & clken_low_pwr) {
>> + mci_writel(host, CLKENA, clk_en_a & ~clken_low_pwr);
>> + mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
>> + SDMMC_CMD_PRV_DAT_WAIT, 0);
>> + }
>> +}
>> +
>> static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
>> {
>> struct dw_mci_slot *slot = mmc_priv(mmc);
>> @@ -871,6 +898,14 @@ static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
>> /* Enable/disable Slot Specific SDIO interrupt */
>> int_mask = mci_readl(host, INTMASK);
>> if (enb) {
>> + /*
>> + * Turn off low power mode if it was enabled. This is a bit of
>> + * a heavy operation and we disable / enable IRQs a lot, so
>> + * we'll leave low power mode disabled and it will get
>> + * re-enabled again in dw_mci_setup_bus().
>> + */
>> + dw_mci_disable_low_power(slot);
>> +
>> mci_writel(host, INTMASK,
>> (int_mask | SDMMC_INT_SDIO(slot->id)));
>> } else {
>
> Basically, disabling low power mode doesn't affect origin working.
> This patch will guarantees to supply the clock while sdio interrupt is activated.
> Looks good to me.
> Chris, feel free to add my ack.
>
> Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
Thanks, pushed to mmc-next for 3.7.
- Chris.
--
Chris Ball <cjb@laptop.org> <http://printf.net/>
One Laptop Per Child
prev parent reply other threads:[~2012-08-08 3:41 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 18:13 [PATCH] mmc: dw_mmc: Disable low power mode if SDIO interrupts are used Doug Anderson
2012-07-21 10:40 ` Will Newton
2012-07-23 2:48 ` Doug Anderson
2012-07-23 9:19 ` Will Newton
2012-07-23 17:00 ` Doug Anderson
2012-07-23 17:02 ` [PATCH v2] " Doug Anderson
2012-07-24 1:17 ` Seungwon Jeon
2012-07-24 16:58 ` Doug Anderson
2012-07-24 1:36 ` Jaehoon Chung
2012-07-24 16:58 ` Doug Anderson
2012-07-24 16:59 ` [PATCH v3] " Doug Anderson
2012-07-25 9:11 ` Will Newton
2012-07-25 10:02 ` Jaehoon Chung
2012-07-25 15:32 ` Doug Anderson
2012-07-25 15:33 ` [PATCH v4] " Doug Anderson
2012-07-26 4:00 ` Seungwon Jeon
2012-08-08 3:40 ` Chris Ball [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87obmmvyno.fsf@octavius.laptop.org \
--to=cjb@laptop.org \
--cc=dianders@chromium.org \
--cc=grundler@chromium.org \
--cc=james.hogan@imgtec.com \
--cc=jh80.chung@samsung.com \
--cc=ki0351.kim@samsung.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=olofj@chromium.org \
--cc=shashidharh@vayavyalabs.com \
--cc=tgih.jun@samsung.com \
--cc=will.newton@imgtec.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).