| Message ID | 20200325143409.13005-3-ludovic.barre@st.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mmc: mmci_sdmmc: fixes and improvements | expand |
On Wed, 25 Mar 2020 at 15:34, Ludovic Barre <ludovic.barre@st.com> wrote: > > In mmci_write_pwr|clk|datactrlreg functions, if the desired value > is equal to corresponding variable (pwr_reg|clk_reg|datactrl_reg), > the value is not written in the register. > > At probe pwr|clk|datactrl_reg of mmci_host structure are initialized > to 0 (kzalloc of mmc_alloc_host). But they does not necessarily reflect > hardware value of these registers, if they are used while boot level. > This is problematic, if we want to write 0 in these registers. It could be, but I don't see that we ever needs to do that - at least not before we have written some other non-zero values to them (through the helper functions). > > This patch initializes pwr|clk|datactrl_reg variables with their > hardware values while probing. Hmm, so in principle this change seems quite okay, but I am hesitant to pick it up - unless it really addresses a problem that you have observed. The reason is, this change may lead to avoiding to re-write the register with the same value it got during boot - and who knows what is best here. Kind regards Uffe > > Signed-off-by: Ludovic Barre <ludovic.barre@st.com> > --- > drivers/mmc/host/mmci.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c > index 647567def612..f378ae18d5dc 100644 > --- a/drivers/mmc/host/mmci.c > +++ b/drivers/mmc/host/mmci.c > @@ -2085,6 +2085,10 @@ static int mmci_probe(struct amba_device *dev, > else if (plat->ocr_mask) > dev_warn(mmc_dev(mmc), "Platform OCR mask is ignored\n"); > > + host->pwr_reg = readl_relaxed(host->base + MMCIPOWER); > + host->clk_reg = readl_relaxed(host->base + MMCICLOCK); > + host->datactrl_reg = readl_relaxed(host->base + MMCIDATACTRL); > + > /* We support these capabilities. */ > mmc->caps |= MMC_CAP_CMD23; > > -- > 2.17.1 >
hi Ulf Le 3/26/20 à 3:27 PM, Ulf Hansson a écrit : > On Wed, 25 Mar 2020 at 15:34, Ludovic Barre <ludovic.barre@st.com> wrote: >> >> In mmci_write_pwr|clk|datactrlreg functions, if the desired value >> is equal to corresponding variable (pwr_reg|clk_reg|datactrl_reg), >> the value is not written in the register. >> >> At probe pwr|clk|datactrl_reg of mmci_host structure are initialized >> to 0 (kzalloc of mmc_alloc_host). But they does not necessarily reflect >> hardware value of these registers, if they are used while boot level. >> This is problematic, if we want to write 0 in these registers. > > It could be, but I don't see that we ever needs to do that - at least > not before we have written some other non-zero values to them (through > the helper functions). > The sdmmc variant is slightly different on pwr_ctrl field of MMCIPOWER register. In classic mmci we have 3 or 2 values: MMCI_PWR_OFF(0x0), MMCI_PWR_UP(0x2)optional, MMCI_PWR_ON(0x3) -When you switch the external power supply off, the software set power-off (0x0). -When you switch the external power supply on, the software first enters the power-up(0x2) phase, and waits until the supply output is stable before moving to the power-on (0x3)phase. On sdmmc we have 3 values: MMCI_PWR_OFF(0x0), MCI_STM32_PWR_CYC(0x2), MMCI_PWR_ON(0x3) -When you switch the external power supply off, the software must MCI_STM32_PWR_CYC(0x2) => This will make that the SDMMC_D[7:0], SDMMC_CMD and SDMMC_CK are driven low, to prevent the card from being supplied through the signal lines. -When you switch the external power supply on, when supply output is stable the MMCI_PWR_OFF(0x0) state can be apply (minimum 1ms) => The SDMMC_D[7:0], SDMMC_CMD and SDMMC_CK are set to drive “1”. After MMCI_PWR_ON(0x3) stat could be set. In fact the last value of power off sequence is different between classic and sdmmc: The classic mmci finish the power off sequence by 0x0, But the sdmmc finish by 0x2, and we must write 0x0 in power on sequence before set MMCI_PWR_ON. The 0x0 value is not written due to kzalloc value of pwr_reg (which not reflect hardware value of pwr register). >> >> This patch initializes pwr|clk|datactrl_reg variables with their >> hardware values while probing. > > Hmm, so in principle this change seems quite okay, but I am hesitant > to pick it up - unless it really addresses a problem that you have > observed. > > The reason is, this change may lead to avoiding to re-write the > register with the same value it got during boot - and who knows what > is best here. I understand your hesitation. If you prefer, I can move the pwr_reg initialisation in sdmmc_variant_init ? Regards Ludo > > Kind regards > Uffe > >> >> Signed-off-by: Ludovic Barre <ludovic.barre@st.com> >> --- >> drivers/mmc/host/mmci.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c >> index 647567def612..f378ae18d5dc 100644 >> --- a/drivers/mmc/host/mmci.c >> +++ b/drivers/mmc/host/mmci.c >> @@ -2085,6 +2085,10 @@ static int mmci_probe(struct amba_device *dev, >> else if (plat->ocr_mask) >> dev_warn(mmc_dev(mmc), "Platform OCR mask is ignored\n"); >> >> + host->pwr_reg = readl_relaxed(host->base + MMCIPOWER); >> + host->clk_reg = readl_relaxed(host->base + MMCICLOCK); >> + host->datactrl_reg = readl_relaxed(host->base + MMCIDATACTRL); >> + >> /* We support these capabilities. */ >> mmc->caps |= MMC_CAP_CMD23; >> >> -- >> 2.17.1 >>
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index 647567def612..f378ae18d5dc 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -2085,6 +2085,10 @@ static int mmci_probe(struct amba_device *dev, else if (plat->ocr_mask) dev_warn(mmc_dev(mmc), "Platform OCR mask is ignored\n"); + host->pwr_reg = readl_relaxed(host->base + MMCIPOWER); + host->clk_reg = readl_relaxed(host->base + MMCICLOCK); + host->datactrl_reg = readl_relaxed(host->base + MMCIDATACTRL); + /* We support these capabilities. */ mmc->caps |= MMC_CAP_CMD23;
In mmci_write_pwr|clk|datactrlreg functions, if the desired value is equal to corresponding variable (pwr_reg|clk_reg|datactrl_reg), the value is not written in the register. At probe pwr|clk|datactrl_reg of mmci_host structure are initialized to 0 (kzalloc of mmc_alloc_host). But they does not necessarily reflect hardware value of these registers, if they are used while boot level. This is problematic, if we want to write 0 in these registers. This patch initializes pwr|clk|datactrl_reg variables with their hardware values while probing. Signed-off-by: Ludovic Barre <ludovic.barre@st.com> --- drivers/mmc/host/mmci.c | 4 ++++ 1 file changed, 4 insertions(+)