On 27/06/2024 14:44, Adrian Hunter wrote:
On 27/06/24 16:09, Jon Hunter wrote:
On 27/06/2024 13:44, Christoph Hellwig wrote:
On Thu, Jun 27, 2024 at 01:30:03PM +0100, Jon Hunter wrote:
I have been testing on both Tegra194 and Tegra234. Both of these set the
above quirk. This would explain why the max_segment_size is rounded down to
65024 in the mmc_alloc_disk() function.
We can check if this is needed but if it is needed then it is not clear
if/how this can be fixed?
The older kernels did this:
if (max_size < PAGE_CACHE_SIZE) {
max_size = PAGE_CACHE_SIZE;
printk(KERN_INFO "%s: set to minimum %d\n",
__func__, max_size);
}
q->limits.max_segment_size = max_size;
so when these kernels actually worked despite the above warning it
must be ok(-ish) to just increase this value. If that is best done
by dropping the quirk, or changing the logic in sdhci.c is something
the maintainers that understand the hardware need to decide.
The patch below gives you the pre-6.9 behavior just without the
boot time warning, but it might not be what was intended by the
quirk:
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 746f4cf7ab0338..0dc3604ac6093a 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -4721,12 +4721,9 @@ int sdhci_setup_host(struct sdhci_host *host)
* be larger than 64 KiB though.
*/
if (host->flags & SDHCI_USE_ADMA) {
- if (host->quirks & SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC) {
+ if (host->quirks & SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC)
host->max_adma = 65532; /* 32-bit alignment */
- mmc->max_seg_size = 65535;
- } else {
- mmc->max_seg_size = 65536;
- }
+ mmc->max_seg_size = 65536;
} else {
mmc->max_seg_size = mmc->max_req_size;
}
As a quick test I removed the quirk for Tegra194 and that did work, which achieves the same thing as the above.
I guess there are two open questions here ...
1. Do we need the quirk for all the current Tegra devices? Thierry and I
can confirm this.
2. For devices that need that quirk and use 64kB pages, what is the
appropriate way to handle this for sdhci controllers?
Probably just do what the block layer was doing e.g.
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 746f4cf7ab03..6a1dea0d8d64 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -4724,6 +4724,13 @@ int sdhci_setup_host(struct sdhci_host *host)
if (host->quirks & SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC) {
host->max_adma = 65532; /* 32-bit alignment */
mmc->max_seg_size = 65535;
+ /*
+ * Block layer cannot accept max_seg_size < PAGE_SIZE
+ * whereas sdhci_adma_table_pre() will anyway split the
+ * descriptor to handle size > max_adma.
+ */
+ if (mmc->max_seg_size < PAGE_SIZE)
+ mmc->max_seg_size = PAGE_SIZE;
} else {
mmc->max_seg_size = 65536;
}
I know that this is expected to work, but just wanted to confirm that
this does work.
Jon
--
nvpublic
