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| author | Thierry Reding <treding@nvidia.com> | 2014-04-07 10:37:44 +0200 |
|---|---|---|
| committer | Christian König <christian.koenig@amd.com> | 2014-04-08 16:12:36 +0200 |
| commit | 1ca2030563534bc0b057df9fddd30fb6257826cb (patch) | |
| tree | 733c5e1f8aecb6bb231c7c07bc3428c21288a2f3 /drivers | |
| parent | c39b06951f1dc2e384650288676c5b7dcc0ec92c (diff) | |
| download | linux-1ca2030563534bc0b057df9fddd30fb6257826cb.tar.gz linux-1ca2030563534bc0b057df9fddd30fb6257826cb.tar.bz2 linux-1ca2030563534bc0b057df9fddd30fb6257826cb.zip | |
drm/tegra: dp: Support address-only I2C-over-AUX transactions
Certain types of I2C-over-AUX transactions require that only the address
is transferred. Detect this by looking at the AUX message's size and set
the address-only bit appropriately.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/tegra/dpaux.c | 44 | ||||
| -rw-r--r-- | drivers/gpu/drm/tegra/dpaux.h | 1 |
2 files changed, 32 insertions, 13 deletions
diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c index d536ed381fbd..005c19bd92df 100644 --- a/drivers/gpu/drm/tegra/dpaux.c +++ b/drivers/gpu/drm/tegra/dpaux.c @@ -99,55 +99,73 @@ static void tegra_dpaux_read_fifo(struct tegra_dpaux *dpaux, u8 *buffer, static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) { - unsigned long value = DPAUX_DP_AUXCTL_TRANSACTREQ; unsigned long timeout = msecs_to_jiffies(250); struct tegra_dpaux *dpaux = to_dpaux(aux); unsigned long status; ssize_t ret = 0; + u32 value; - if (msg->size < 1 || msg->size > 16) + /* Tegra has 4x4 byte DP AUX transmit and receive FIFOs. */ + if (msg->size > 16) return -EINVAL; - tegra_dpaux_writel(dpaux, msg->address, DPAUX_DP_AUXADDR); + /* + * Allow zero-sized messages only for I2C, in which case they specify + * address-only transactions. + */ + if (msg->size < 1) { + switch (msg->request & ~DP_AUX_I2C_MOT) { + case DP_AUX_I2C_WRITE: + case DP_AUX_I2C_READ: + value = DPAUX_DP_AUXCTL_CMD_ADDRESS_ONLY; + break; + + default: + return -EINVAL; + } + } else { + /* For non-zero-sized messages, set the CMDLEN field. */ + value = DPAUX_DP_AUXCTL_CMDLEN(msg->size - 1); + } switch (msg->request & ~DP_AUX_I2C_MOT) { case DP_AUX_I2C_WRITE: if (msg->request & DP_AUX_I2C_MOT) - value = DPAUX_DP_AUXCTL_CMD_MOT_WR; + value |= DPAUX_DP_AUXCTL_CMD_MOT_WR; else - value = DPAUX_DP_AUXCTL_CMD_I2C_WR; + value |= DPAUX_DP_AUXCTL_CMD_I2C_WR; break; case DP_AUX_I2C_READ: if (msg->request & DP_AUX_I2C_MOT) - value = DPAUX_DP_AUXCTL_CMD_MOT_RD; + value |= DPAUX_DP_AUXCTL_CMD_MOT_RD; else - value = DPAUX_DP_AUXCTL_CMD_I2C_RD; + value |= DPAUX_DP_AUXCTL_CMD_I2C_RD; break; case DP_AUX_I2C_STATUS: if (msg->request & DP_AUX_I2C_MOT) - value = DPAUX_DP_AUXCTL_CMD_MOT_RQ; + value |= DPAUX_DP_AUXCTL_CMD_MOT_RQ; else - value = DPAUX_DP_AUXCTL_CMD_I2C_RQ; + value |= DPAUX_DP_AUXCTL_CMD_I2C_RQ; break; case DP_AUX_NATIVE_WRITE: - value = DPAUX_DP_AUXCTL_CMD_AUX_WR; + value |= DPAUX_DP_AUXCTL_CMD_AUX_WR; break; case DP_AUX_NATIVE_READ: - value = DPAUX_DP_AUXCTL_CMD_AUX_RD; + value |= DPAUX_DP_AUXCTL_CMD_AUX_RD; break; default: return -EINVAL; } - value |= DPAUX_DP_AUXCTL_CMDLEN(msg->size - 1); + tegra_dpaux_writel(dpaux, msg->address, DPAUX_DP_AUXADDR); tegra_dpaux_writel(dpaux, value, DPAUX_DP_AUXCTL); if ((msg->request & DP_AUX_I2C_READ) == 0) { @@ -198,7 +216,7 @@ static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux, break; } - if (msg->reply == DP_AUX_NATIVE_REPLY_ACK) { + if ((msg->size > 0) && (msg->reply == DP_AUX_NATIVE_REPLY_ACK)) { if (msg->request & DP_AUX_I2C_READ) { size_t count = value & DPAUX_DP_AUXSTAT_REPLY_MASK; diff --git a/drivers/gpu/drm/tegra/dpaux.h b/drivers/gpu/drm/tegra/dpaux.h index 4f5bf10fdff9..806e245ca787 100644 --- a/drivers/gpu/drm/tegra/dpaux.h +++ b/drivers/gpu/drm/tegra/dpaux.h @@ -32,6 +32,7 @@ #define DPAUX_DP_AUXCTL_CMD_I2C_RQ (2 << 12) #define DPAUX_DP_AUXCTL_CMD_I2C_RD (1 << 12) #define DPAUX_DP_AUXCTL_CMD_I2C_WR (0 << 12) +#define DPAUX_DP_AUXCTL_CMD_ADDRESS_ONLY (1 << 8) #define DPAUX_DP_AUXCTL_CMDLEN(x) ((x) & 0xff) #define DPAUX_DP_AUXSTAT 0x31 |