Re: [PATCH v2 2/7] mmc: sdhci-of-arasan: Fix SDHCI_RESET_ALL for CQHCI

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On 10/19/22 23:29, Adrian Hunter wrote:
On 20/10/22 01:19, Brian Norris wrote:
On Wed, Oct 19, 2022 at 02:59:39PM -0700, Florian Fainelli wrote:
On 10/19/22 14:54, Brian Norris wrote:
The same bug was already found and fixed for two other drivers, in v5.7
and v5.9:

5cf583f1fb9c mmc: sdhci-msm: Deactivate CQE during SDHC reset
df57d73276b8 mmc: sdhci-pci: Fix SDHCI_RESET_ALL for CQHCI for Intel GLK-based controllers

The latter is especially prescient, saying "other drivers using CQHCI
might benefit from a similar change, if they also have CQHCI reset by
SDHCI_RESET_ALL."

--- a/drivers/mmc/host/sdhci-of-arasan.c
+++ b/drivers/mmc/host/sdhci-of-arasan.c
@@ -366,6 +366,9 @@ static void sdhci_arasan_reset(struct sdhci_host *host, u8 mask)
   	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
   	struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
+	if ((host->mmc->caps2 & MMC_CAP2_CQE) && (mask & SDHCI_RESET_ALL))
+		cqhci_deactivate(host->mmc);
+
   	sdhci_reset(host, mask);

Cannot this be absorbed by sdhci_reset() that all of these drivers appear to
be utilizing since you have access to the host and the mask to make that
decision?

It potentially could.

I don't know if this is a specified SDHCI behavior that really belongs
in the common helper, or if this is just a commonly-shared behavior. Per
the comments I quote above ("if they also have CQHCI reset by
SDHCI_RESET_ALL"), I chose to leave that as an implementation-specific
behavior.

I suppose it's not all that harmful to do this even if some SDHCI
controller doesn't have the same behavior/quirk.

I guess I also don't know if any SDHCI controllers will support command
queueing (MMC_CAP2_CQE) via somethings *besides* CQHCI. I see
CQE support in sdhci-sprd.c without CQHCI, although that driver doesn't
set MMC_CAP2_CQE.

SDHCI and CQHCI are separate modules and are not dependent, so they cannot
call into each other directly (and should not).  A new CQE API would be
needed in mmc_cqe_ops e.g. (*cqe_notify_reset)(struct mmc_host *host),
and wrapped in mmc/host.h:

static inline void mmc_cqe_notify_reset(struct mmc_host *host)
{
	if (host->cqe_ops->cqe_notify_reset)
		host->cqe_ops->cqe_notify_reset(host);
}

Alternatively, you could make a new module for SDHCI/CQHCI helper functions,
although in this case there is so little code it could be static inline and
added in a new include file instead, say sdhci-cqhci.h e.g.

#include "cqhci.h"
#include "sdhci.h"

static inline void sdhci_cqhci_reset(struct sdhci_host *host, u8 mask)
{
	if ((host->mmc->caps2 & MMC_CAP2_CQE) && (mask & SDHCI_RESET_ALL) &&
	    host->mmc->cqe_private)
		cqhci_deactivate(host->mmc);
	sdhci_reset(host, mask);
}


I like the simplicity of the inline helper, especially towards backports. May suggest to name it sdhci_and_cqhci_reset() to illustrate that it does both, and does not apply specifically CQHCI that would be "embedded" into SDHCI, but your call here.
--
Florian




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