Re: [PATCH v1 2/5] mmc: sdhci_am654: Write ITAPDLY for DDR52 timing

From: Andrew Davis
Date: Thu Feb 01 2024 - 14:36:51 EST


On 1/31/24 3:50 PM, Judith Mendez wrote:
For DDR52 timing, DLL is enabled but tuning is not carried
out, therefore the ITAPDLY value in PHY CTRL 4 register is
not correct. Fix this by writing ITAPDLY after enabling DLL.

Fixes: a161c45f2979 ("mmc: sdhci_am654: Enable DLL only for some speed modes")
Signed-off-by: Judith Mendez <jm@xxxxxx>
---
drivers/mmc/host/sdhci_am654.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index a3798c9912f6..ff18a274b6f2 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -170,7 +170,19 @@ struct sdhci_am654_driver_data {
#define DLL_CALIB (1 << 4)
};
-static void sdhci_am654_setup_dll(struct sdhci_host *host, unsigned int clock)
+static void sdhci_am654_write_itapdly(struct sdhci_am654_data *sdhci_am654,
+ u32 itapdly)

This patch is confusing, looks like you switched the place of these two
functions, but diff is not really liking that. You can mess with
--diff-algorithm and the like to get a more readable patch. But in
this case why switch their spots at all?

Seems to be so you can call sdhci_am654_write_itapdly() from
sdhci_am654_setup_dll() without a forward declaration, instead
why not just call sdhci_am654_write_itapdly() after calling
sdhci_am654_setup_dll() below. That also saves to from having
to pass in `timing` to sdhci_am654_write_itapdly() just to
have it pass it right through to sdhci_am654_setup_dll().

Andrew

+{
+ /* Set ITAPCHGWIN before writing to ITAPDLY */
+ regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPCHGWIN_MASK,
+ 0x1 << ITAPCHGWIN_SHIFT);
+ regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPDLYSEL_MASK,
+ itapdly << ITAPDLYSEL_SHIFT);
+ regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPCHGWIN_MASK, 0);
+}
+
+static void sdhci_am654_setup_dll(struct sdhci_host *host, unsigned int clock,
+ unsigned char timing)
{
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
@@ -236,17 +248,8 @@ static void sdhci_am654_setup_dll(struct sdhci_host *host, unsigned int clock)
dev_err(mmc_dev(host->mmc), "DLL failed to relock\n");
return;
}
-}
-static void sdhci_am654_write_itapdly(struct sdhci_am654_data *sdhci_am654,
- u32 itapdly)
-{
- /* Set ITAPCHGWIN before writing to ITAPDLY */
- regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPCHGWIN_MASK,
- 1 << ITAPCHGWIN_SHIFT);
- regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPDLYSEL_MASK,
- itapdly << ITAPDLYSEL_SHIFT);
- regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPCHGWIN_MASK, 0);
+ sdhci_am654_write_itapdly(sdhci_am654, sdhci_am654->itap_del_sel[timing]);
}
static void sdhci_am654_setup_delay_chain(struct sdhci_am654_data *sdhci_am654,
@@ -298,7 +301,7 @@ static void sdhci_am654_set_clock(struct sdhci_host *host, unsigned int clock)
regmap_update_bits(sdhci_am654->base, PHY_CTRL4, mask, val);
if (timing > MMC_TIMING_UHS_SDR25 && clock >= CLOCK_TOO_SLOW_HZ) {
- sdhci_am654_setup_dll(host, clock);
+ sdhci_am654_setup_dll(host, clock, timing);
sdhci_am654->dll_enable = true;
} else {
sdhci_am654_setup_delay_chain(sdhci_am654, timing);