On Fri, 2013-07-26 at 23:52 +0200, Paul Bolle wrote:
> A laptop I use prints a warning twice at every boot and every resume:
> sdhci-pci 0000:05:00.2: Will use DMA mode even though HW doesn't fully claim to support it.
> sdhci-pci 0000:05:00.2: Will use DMA mode even though HW doesn't fully claim to support it.
>
> These warnings are always printed in pairs.
>
> This message shouldn't be a warning, but a notice, as there's little the
> user is able to do about the choice for DMA mode. The only way to
> overrule it seems to be the use of (undocumented) debug quirks for the
> sdhci module.
>
> And, furthermore, this notice needs only be printed once. Everything here
> depends on the hardware of the SD host controller used, which can't
> change.
>
> Signed-off-by: Paul Bolle <pebolle@xxxxxxxxxx>
> ---
> 0) Tested on v3.10.3. Compile tested for v3.11-rc2.
Did anyone have a look at this patch? It compiles cleanly on top of
v3.13-rc4. It also does what it claims to do when running v3.13-rc4.
> 1) Note that this warning is printed twice at boot (or module load)
> because the call chain is:
> sdhci_add_host()
> host->ops->enable_dma() = sdhci_pci_enable_dma()
> sdhci_init()
> sdhci_reset()
> host->ops->enable_dma() = sdhci_pci_enable_dma()
>
> (And, if I understand the code correctly, for non-quirky host
> controllers it can even print the warning three times!)
>
> The call chain at resume is:
> sdhci_resume_host()
> host->ops->enable_dma() = sdhci_pci_enable_dma()
> sdhci_init()
> sdhci_reset()
> host->ops->enable_dma() = sdhci_pci_enable_dma()
>
> 2) Note that the patch would be simpler if it's OK to print this message
> once per _module_ and not, as this patch does, once per _host
> controller_. Are there systems that use more than one SD host
> controller, both with different (advertised) DMA capabilities?
>
> drivers/mmc/host/sdhci-pci.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci.c b/drivers/mmc/host/sdhci-pci.c
> index d7d6bc8..69fc509 100644
> --- a/drivers/mmc/host/sdhci-pci.c
> +++ b/drivers/mmc/host/sdhci-pci.c
> @@ -88,6 +88,7 @@ struct sdhci_pci_chip {
> unsigned int quirks;
> unsigned int quirks2;
> bool allow_runtime_pm;
> + bool use_sdma_notified;
> const struct sdhci_pci_fixes *fixes;
>
> int num_slots; /* Slots on controller */
> @@ -997,17 +998,21 @@ MODULE_DEVICE_TABLE(pci, pci_ids);
> static int sdhci_pci_enable_dma(struct sdhci_host *host)
> {
> struct sdhci_pci_slot *slot;
> + struct sdhci_pci_chip *chip;
> struct pci_dev *pdev;
> int ret;
>
> slot = sdhci_priv(host);
> - pdev = slot->chip->pdev;
> + chip = slot->chip;
> + pdev = chip->pdev;
>
> if (((pdev->class & 0xFFFF00) == (PCI_CLASS_SYSTEM_SDHCI << 8)) &&
> ((pdev->class & 0x0000FF) != PCI_SDHCI_IFDMA) &&
> - (host->flags & SDHCI_USE_SDMA)) {
> - dev_warn(&pdev->dev, "Will use DMA mode even though HW "
> - "doesn't fully claim to support it.\n");
> + (host->flags & SDHCI_USE_SDMA) &&
> + (chip->use_sdma_notified == false)) {
> + dev_notice(&pdev->dev, "Will use DMA mode even though HW "
> + "doesn't fully claim to support it.\n");
> + chip->use_sdma_notified = true;
> }
>
> ret = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
> @@ -1504,6 +1509,7 @@ static int sdhci_pci_probe(struct pci_dev *pdev,
> chip->allow_runtime_pm = chip->fixes->allow_runtime_pm;
> }
> chip->num_slots = slots;
> + chip->use_sdma_notified = false;
>
> pci_set_drvdata(pdev, chip);
>
Paul Bolle
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