Re: [RFC v2 2/2] mmc: sdhci: Ignore capability register when it comes to speeds and use DT binding instead when sdhci-cap-speed-modes-broken is set.

On Tue, Oct 25, 2016 at 02:30:25PM +0300, Adrian Hunter wrote:

On 24/10/16 18:48, Zach Brown wrote:

quoted

On Mon, Oct 24, 2016 at 10:34:46AM +0300, Adrian Hunter wrote:

quoted

On 22/10/16 00:35, Zach Brown wrote:

quoted

When the sdhci-cap-speed-modes-broken DT property is set, the driver
will ignore the bits of the capability registers that correspond to
speed modes.

Signed-off-by: Zach Brown <redacted>
---
 drivers/mmc/host/sdhci.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 1e25b01..59c62d3 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c

@@ -22,6 +22,7 @@
 #include <linux/scatterlist.h>
 #include <linux/regulator/consumer.h>
 #include <linux/pm_runtime.h>
+#include <linux/of.h>

 #include <linux/leds.h>

@@ -3013,10 +3014,19 @@ void __sdhci_read_caps(struct sdhci_host *host, u16 *ver, u32 *caps, u32 *caps1)

 	host->caps = caps ? *caps : sdhci_readl(host, SDHCI_CAPABILITIES);

+	if (of_property_read_bool(mmc_dev(host->mmc)->of_node,
+				  "sdhci-cap-speed-modes-broken"))

It rather begs the question: if you are going to do something sdhci
specific, why not just read the whole of the caps register from DT?

Throwing out the whole of the caps register seems like overkill. Also

What about 2 values: one for the 64-bit caps register and one for a 64-bit
mask of bits to override.  That way you can select which bits to override
and what to override them to.

I like this idea. I sent a RFC of it. 

quoted

there are some things set by the caps that are not available in the DT.
For example, SDHCI_CAN_64BIT is set by the cap register and is used in
sdhci_setup_host to set host->flags SDHCI_USE_64_BIT_DMA.

Not sure what you mean.

Your suggestion addresses my concern. So it's not an issue.