diff options
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/pxa2xx_spi.c | 59 |
1 files changed, 48 insertions, 11 deletions
diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c index 34c7c9875681..a7b9070e1b46 100644 --- a/drivers/spi/pxa2xx_spi.c +++ b/drivers/spi/pxa2xx_spi.c @@ -144,7 +144,6 @@ struct driver_data { size_t tx_map_len; u8 n_bytes; u32 dma_width; - int cs_change; int (*write)(struct driver_data *drv_data); int (*read)(struct driver_data *drv_data); irqreturn_t (*transfer_handler)(struct driver_data *drv_data); @@ -406,8 +405,45 @@ static void giveback(struct driver_data *drv_data) struct spi_transfer, transfer_list); + /* Delay if requested before any change in chip select */ + if (last_transfer->delay_usecs) + udelay(last_transfer->delay_usecs); + + /* Drop chip select UNLESS cs_change is true or we are returning + * a message with an error, or next message is for another chip + */ if (!last_transfer->cs_change) drv_data->cs_control(PXA2XX_CS_DEASSERT); + else { + struct spi_message *next_msg; + + /* Holding of cs was hinted, but we need to make sure + * the next message is for the same chip. Don't waste + * time with the following tests unless this was hinted. + * + * We cannot postpone this until pump_messages, because + * after calling msg->complete (below) the driver that + * sent the current message could be unloaded, which + * could invalidate the cs_control() callback... + */ + + /* get a pointer to the next message, if any */ + spin_lock_irqsave(&drv_data->lock, flags); + if (list_empty(&drv_data->queue)) + next_msg = NULL; + else + next_msg = list_entry(drv_data->queue.next, + struct spi_message, queue); + spin_unlock_irqrestore(&drv_data->lock, flags); + + /* see if the next and current messages point + * to the same chip + */ + if (next_msg && next_msg->spi != msg->spi) + next_msg = NULL; + if (!next_msg || msg->state == ERROR_STATE) + drv_data->cs_control(PXA2XX_CS_DEASSERT); + } msg->state = NULL; if (msg->complete) @@ -490,10 +526,9 @@ static void dma_transfer_complete(struct driver_data *drv_data) msg->actual_length += drv_data->len - (drv_data->rx_end - drv_data->rx); - /* Release chip select if requested, transfer delays are - * handled in pump_transfers */ - if (drv_data->cs_change) - drv_data->cs_control(PXA2XX_CS_DEASSERT); + /* Transfer delays and chip select release are + * handled in pump_transfers or giveback + */ /* Move to next transfer */ msg->state = next_transfer(drv_data); @@ -602,10 +637,9 @@ static void int_transfer_complete(struct driver_data *drv_data) drv_data->cur_msg->actual_length += drv_data->len - (drv_data->rx_end - drv_data->rx); - /* Release chip select if requested, transfer delays are - * handled in pump_transfers */ - if (drv_data->cs_change) - drv_data->cs_control(PXA2XX_CS_DEASSERT); + /* Transfer delays and chip select release are + * handled in pump_transfers or giveback + */ /* Move to next transfer */ drv_data->cur_msg->state = next_transfer(drv_data); @@ -840,13 +874,17 @@ static void pump_transfers(unsigned long data) return; } - /* Delay if requested at end of transfer*/ + /* Delay if requested at end of transfer before CS change */ if (message->state == RUNNING_STATE) { previous = list_entry(transfer->transfer_list.prev, struct spi_transfer, transfer_list); if (previous->delay_usecs) udelay(previous->delay_usecs); + + /* Drop chip select only if cs_change is requested */ + if (previous->cs_change) + drv_data->cs_control(PXA2XX_CS_DEASSERT); } /* Check transfer length */ @@ -878,7 +916,6 @@ static void pump_transfers(unsigned long data) drv_data->len = transfer->len & DCMD_LENGTH; drv_data->write = drv_data->tx ? chip->write : null_writer; drv_data->read = drv_data->rx ? chip->read : null_reader; - drv_data->cs_change = transfer->cs_change; /* Change speed and bit per word on a per transfer */ cr0 = chip->cr0; |